bpo-40939: Remove the old parser (GH-20768)

This commit removes the old parser, the deprecated parser module, the old parser compatibility flags and environment variables and all associated support code and documentation.

1 files changed, 0 insertions, 5289 deletions

diff --git a/Python/ast.c b/Python/ast.c
index 408591f..d7feb8c 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -550,5295 +550,6 @@ PyAST_Validate(mod_ty mod)
     return res;
 }
 
-/* This is done here, so defines like "test" don't interfere with AST use above. */
-#include "grammar.h"
-#include "parsetok.h"
-#include "graminit.h"
-
-/* Data structure used internally */
-struct compiling {
-    PyArena *c_arena; /* Arena for allocating memory. */
-    PyObject *c_filename; /* filename */
-    PyObject *c_normalize; /* Normalization function from unicodedata. */
-    int c_feature_version; /* Latest minor version of Python for allowed features */
-};
-
-static asdl_seq *seq_for_testlist(struct compiling *, const node *);
-static expr_ty ast_for_expr(struct compiling *, const node *);
-static stmt_ty ast_for_stmt(struct compiling *, const node *);
-static asdl_seq *ast_for_suite(struct compiling *c, const node *n);
-static asdl_seq *ast_for_exprlist(struct compiling *, const node *,
-                                  expr_context_ty);
-static expr_ty ast_for_testlist(struct compiling *, const node *);
-static stmt_ty ast_for_classdef(struct compiling *, const node *, asdl_seq *);
-
-static stmt_ty ast_for_with_stmt(struct compiling *, const node *, bool);
-static stmt_ty ast_for_for_stmt(struct compiling *, const node *, bool);
-
-/* Note different signature for ast_for_call */
-static expr_ty ast_for_call(struct compiling *, const node *, expr_ty,
-                            const node *, const node *, const node *);
-
-static PyObject *parsenumber(struct compiling *, const char *);
-static expr_ty parsestrplus(struct compiling *, const node *n);
-static void get_last_end_pos(asdl_seq *, int *, int *);
-
-#define COMP_GENEXP   0
-#define COMP_LISTCOMP 1
-#define COMP_SETCOMP  2
-
-static int
-init_normalization(struct compiling *c)
-{
-    PyObject *m = PyImport_ImportModuleNoBlock("unicodedata");
-    if (!m)
-        return 0;
-    c->c_normalize = PyObject_GetAttrString(m, "normalize");
-    Py_DECREF(m);
-    if (!c->c_normalize)
-        return 0;
-    return 1;
-}
-
-static identifier
-new_identifier(const char *n, struct compiling *c)
-{
-    PyObject *id = PyUnicode_DecodeUTF8(n, strlen(n), NULL);
-    if (!id)
-        return NULL;
-    /* PyUnicode_DecodeUTF8 should always return a ready string. */
-    assert(PyUnicode_IS_READY(id));
-    /* Check whether there are non-ASCII characters in the
-       identifier; if so, normalize to NFKC. */
-    if (!PyUnicode_IS_ASCII(id)) {
-        PyObject *id2;
-        if (!c->c_normalize && !init_normalization(c)) {
-            Py_DECREF(id);
-            return NULL;
-        }
-        PyObject *form = PyUnicode_InternFromString("NFKC");
-        if (form == NULL) {
-            Py_DECREF(id);
-            return NULL;
-        }
-        PyObject *args[2] = {form, id};
-        id2 = _PyObject_FastCall(c->c_normalize, args, 2);
-        Py_DECREF(id);
-        Py_DECREF(form);
-        if (!id2)
-            return NULL;
-        if (!PyUnicode_Check(id2)) {
-            PyErr_Format(PyExc_TypeError,
-                         "unicodedata.normalize() must return a string, not "
-                         "%.200s",
-                         _PyType_Name(Py_TYPE(id2)));
-            Py_DECREF(id2);
-            return NULL;
-        }
-        id = id2;
-    }
-    PyUnicode_InternInPlace(&id);
-    if (PyArena_AddPyObject(c->c_arena, id) < 0) {
-        Py_DECREF(id);
-        return NULL;
-    }
-    return id;
-}
-
-#define NEW_IDENTIFIER(n) new_identifier(STR(n), c)
-
-static int
-ast_error(struct compiling *c, const node *n, const char *errmsg, ...)
-{
-    PyObject *value, *errstr, *loc, *tmp;
-    va_list va;
-
-    va_start(va, errmsg);
-    errstr = PyUnicode_FromFormatV(errmsg, va);
-    va_end(va);
-    if (!errstr) {
-        return 0;
-    }
-    loc = PyErr_ProgramTextObject(c->c_filename, LINENO(n));
-    if (!loc) {
-        Py_INCREF(Py_None);
-        loc = Py_None;
-    }
-    tmp = Py_BuildValue("(OiiN)", c->c_filename, LINENO(n), n->n_col_offset + 1, loc);
-    if (!tmp) {
-        Py_DECREF(errstr);
-        return 0;
-    }
-    value = PyTuple_Pack(2, errstr, tmp);
-    Py_DECREF(errstr);
-    Py_DECREF(tmp);
-    if (value) {
-        PyErr_SetObject(PyExc_SyntaxError, value);
-        Py_DECREF(value);
-    }
-    return 0;
-}
-
-/* num_stmts() returns number of contained statements.
-
-   Use this routine to determine how big a sequence is needed for
-   the statements in a parse tree.  Its raison d'etre is this bit of
-   grammar:
-
-   stmt: simple_stmt | compound_stmt
-   simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
-
-   A simple_stmt can contain multiple small_stmt elements joined
-   by semicolons.  If the arg is a simple_stmt, the number of
-   small_stmt elements is returned.
-*/
-
-static string
-new_type_comment(const char *s, struct compiling *c)
-{
-    PyObject *res = PyUnicode_DecodeUTF8(s, strlen(s), NULL);
-    if (res == NULL)
-        return NULL;
-    if (PyArena_AddPyObject(c->c_arena, res) < 0) {
-        Py_DECREF(res);
-        return NULL;
-    }
-    return res;
-}
-#define NEW_TYPE_COMMENT(n) new_type_comment(STR(n), c)
-
-static int
-num_stmts(const node *n)
-{
-    int i, l;
-    node *ch;
-
-    switch (TYPE(n)) {
-        case single_input:
-            if (TYPE(CHILD(n, 0)) == NEWLINE)
-                return 0;
-            else
-                return num_stmts(CHILD(n, 0));
-        case file_input:
-            l = 0;
-            for (i = 0; i < NCH(n); i++) {
-                ch = CHILD(n, i);
-                if (TYPE(ch) == stmt)
-                    l += num_stmts(ch);
-            }
-            return l;
-        case stmt:
-            return num_stmts(CHILD(n, 0));
-        case compound_stmt:
-            return 1;
-        case simple_stmt:
-            return NCH(n) / 2; /* Divide by 2 to remove count of semi-colons */
-        case suite:
-        case func_body_suite:
-            /* func_body_suite: simple_stmt | NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT */
-            /* suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT */
-            if (NCH(n) == 1)
-                return num_stmts(CHILD(n, 0));
-            else {
-                i = 2;
-                l = 0;
-                if (TYPE(CHILD(n, 1)) == TYPE_COMMENT)
-                    i += 2;
-                for (; i < (NCH(n) - 1); i++)
-                    l += num_stmts(CHILD(n, i));
-                return l;
-            }
-        default: {
-            _Py_FatalErrorFormat(__func__, "Non-statement found: %d %d",
-                                 TYPE(n), NCH(n));
-        }
-    }
-    Py_UNREACHABLE();
-}
-
-/* Transform the CST rooted at node * to the appropriate AST
-*/
-
-mod_ty
-PyAST_FromNodeObject(const node *n, PyCompilerFlags *flags,
-                     PyObject *filename, PyArena *arena)
-{
-    int i, j, k, num;
-    asdl_seq *stmts = NULL;
-    asdl_seq *type_ignores = NULL;
-    stmt_ty s;
-    node *ch;
-    struct compiling c;
-    mod_ty res = NULL;
-    asdl_seq *argtypes = NULL;
-    expr_ty ret, arg;
-
-    c.c_arena = arena;
-    /* borrowed reference */
-    c.c_filename = filename;
-    c.c_normalize = NULL;
-    c.c_feature_version = flags ? flags->cf_feature_version : PY_MINOR_VERSION;
-
-    if (TYPE(n) == encoding_decl)
-        n = CHILD(n, 0);
-
-    k = 0;
-    switch (TYPE(n)) {
-        case file_input:
-            stmts = _Py_asdl_seq_new(num_stmts(n), arena);
-            if (!stmts)
-                goto out;
-            for (i = 0; i < NCH(n) - 1; i++) {
-                ch = CHILD(n, i);
-                if (TYPE(ch) == NEWLINE)
-                    continue;
-                REQ(ch, stmt);
-                num = num_stmts(ch);
-                if (num == 1) {
-                    s = ast_for_stmt(&c, ch);
-                    if (!s)
-                        goto out;
-                    asdl_seq_SET(stmts, k++, s);
-                }
-                else {
-                    ch = CHILD(ch, 0);
-                    REQ(ch, simple_stmt);
-                    for (j = 0; j < num; j++) {
-                        s = ast_for_stmt(&c, CHILD(ch, j * 2));
-                        if (!s)
-                            goto out;
-                        asdl_seq_SET(stmts, k++, s);
-                    }
-                }
-            }
-
-            /* Type ignores are stored under the ENDMARKER in file_input. */
-            ch = CHILD(n, NCH(n) - 1);
-            REQ(ch, ENDMARKER);
-            num = NCH(ch);
-            type_ignores = _Py_asdl_seq_new(num, arena);
-            if (!type_ignores)
-                goto out;
-
-            for (i = 0; i < num; i++) {
-                string type_comment = new_type_comment(STR(CHILD(ch, i)), &c);
-                if (!type_comment)
-                    goto out;
-                type_ignore_ty ti = TypeIgnore(LINENO(CHILD(ch, i)), type_comment, arena);
-                if (!ti)
-                   goto out;
-               asdl_seq_SET(type_ignores, i, ti);
-            }
-
-            res = Module(stmts, type_ignores, arena);
-            break;
-        case eval_input: {
-            expr_ty testlist_ast;
-
-            /* XXX Why not comp_for here? */
-            testlist_ast = ast_for_testlist(&c, CHILD(n, 0));
-            if (!testlist_ast)
-                goto out;
-            res = Expression(testlist_ast, arena);
-            break;
-        }
-        case single_input:
-            if (TYPE(CHILD(n, 0)) == NEWLINE) {
-                stmts = _Py_asdl_seq_new(1, arena);
-                if (!stmts)
-                    goto out;
-                asdl_seq_SET(stmts, 0, Pass(n->n_lineno, n->n_col_offset,
-                                            n->n_end_lineno, n->n_end_col_offset,
-                                            arena));
-                if (!asdl_seq_GET(stmts, 0))
-                    goto out;
-                res = Interactive(stmts, arena);
-            }
-            else {
-                n = CHILD(n, 0);
-                num = num_stmts(n);
-                stmts = _Py_asdl_seq_new(num, arena);
-                if (!stmts)
-                    goto out;
-                if (num == 1) {
-                    s = ast_for_stmt(&c, n);
-                    if (!s)
-                        goto out;
-                    asdl_seq_SET(stmts, 0, s);
-                }
-                else {
-                    /* Only a simple_stmt can contain multiple statements. */
-                    REQ(n, simple_stmt);
-                    for (i = 0; i < NCH(n); i += 2) {
-                        if (TYPE(CHILD(n, i)) == NEWLINE)
-                            break;
-                        s = ast_for_stmt(&c, CHILD(n, i));
-                        if (!s)
-                            goto out;
-                        asdl_seq_SET(stmts, i / 2, s);
-                    }
-                }
-
-                res = Interactive(stmts, arena);
-            }
-            break;
-        case func_type_input:
-            n = CHILD(n, 0);
-            REQ(n, func_type);
-
-            if (TYPE(CHILD(n, 1)) == typelist) {
-                ch = CHILD(n, 1);
-                /* this is overly permissive -- we don't pay any attention to
-                 * stars on the args -- just parse them into an ordered list */
-                num = 0;
-                for (i = 0; i < NCH(ch); i++) {
-                    if (TYPE(CHILD(ch, i)) == test) {
-                        num++;
-                    }
-                }
-
-                argtypes = _Py_asdl_seq_new(num, arena);
-                if (!argtypes)
-                    goto out;
-
-                j = 0;
-                for (i = 0; i < NCH(ch); i++) {
-                    if (TYPE(CHILD(ch, i)) == test) {
-                        arg = ast_for_expr(&c, CHILD(ch, i));
-                        if (!arg)
-                            goto out;
-                        asdl_seq_SET(argtypes, j++, arg);
-                    }
-                }
-            }
-            else {
-                argtypes = _Py_asdl_seq_new(0, arena);
-                if (!argtypes)
-                    goto out;
-            }
-
-            ret = ast_for_expr(&c, CHILD(n, NCH(n) - 1));
-            if (!ret)
-                goto out;
-            res = FunctionType(argtypes, ret, arena);
-            break;
-        default:
-            PyErr_Format(PyExc_SystemError,
-                         "invalid node %d for PyAST_FromNode", TYPE(n));
-            goto out;
-    }
- out:
-    if (c.c_normalize) {
-        Py_DECREF(c.c_normalize);
-    }
-    return res;
-}
-
-mod_ty
-PyAST_FromNode(const node *n, PyCompilerFlags *flags, const char *filename_str,
-               PyArena *arena)
-{
-    mod_ty mod;
-    PyObject *filename;
-    filename = PyUnicode_DecodeFSDefault(filename_str);
-    if (filename == NULL)
-        return NULL;
-    mod = PyAST_FromNodeObject(n, flags, filename, arena);
-    Py_DECREF(filename);
-    return mod;
-
-}
-
-/* Return the AST repr. of the operator represented as syntax (|, ^, etc.)
-*/
-
-static operator_ty
-get_operator(struct compiling *c, const node *n)
-{
-    switch (TYPE(n)) {
-        case VBAR:
-            return BitOr;
-        case CIRCUMFLEX:
-            return BitXor;
-        case AMPER:
-            return BitAnd;
-        case LEFTSHIFT:
-            return LShift;
-        case RIGHTSHIFT:
-            return RShift;
-        case PLUS:
-            return Add;
-        case MINUS:
-            return Sub;
-        case STAR:
-            return Mult;
-        case AT:
-            if (c->c_feature_version < 5) {
-                ast_error(c, n,
-                          "The '@' operator is only supported in Python 3.5 and greater");
-                return (operator_ty)0;
-            }
-            return MatMult;
-        case SLASH:
-            return Div;
-        case DOUBLESLASH:
-            return FloorDiv;
-        case PERCENT:
-            return Mod;
-        default:
-            return (operator_ty)0;
-    }
-}
-
-static const char * const FORBIDDEN[] = {
-    "None",
-    "True",
-    "False",
-    "__debug__",
-    NULL,
-};
-
-static int
-forbidden_name(struct compiling *c, identifier name, const node *n,
-               int full_checks)
-{
-    assert(PyUnicode_Check(name));
-    const char * const *p = FORBIDDEN;
-    if (!full_checks) {
-        /* In most cases, the parser will protect True, False, and None
-           from being assign to. */
-        p += 3;
-    }
-    for (; *p; p++) {
-        if (_PyUnicode_EqualToASCIIString(name, *p)) {
-            ast_error(c, n, "cannot assign to %U", name);
-            return 1;
-        }
-    }
-    return 0;
-}
-
-static expr_ty
-copy_location(expr_ty e, const node *n, const node *end)
-{
-    if (e) {
-        e->lineno = LINENO(n);
-        e->col_offset = n->n_col_offset;
-        e->end_lineno = end->n_end_lineno;
-        e->end_col_offset = end->n_end_col_offset;
-    }
-    return e;
-}
-
-static const char *
-get_expr_name(expr_ty e)
-{
-    switch (e->kind) {
-        case Attribute_kind:
-            return "attribute";
-        case Subscript_kind:
-            return "subscript";
-        case Starred_kind:
-            return "starred";
-        case Name_kind:
-            return "name";
-        case List_kind:
-            return "list";
-        case Tuple_kind:
-            return "tuple";
-        case Lambda_kind:
-            return "lambda";
-        case Call_kind:
-            return "function call";
-        case BoolOp_kind:
-        case BinOp_kind:
-        case UnaryOp_kind:
-            return "operator";
-        case GeneratorExp_kind:
-            return "generator expression";
-        case Yield_kind:
-        case YieldFrom_kind:
-            return "yield expression";
-        case Await_kind:
-            return "await expression";
-        case ListComp_kind:
-            return "list comprehension";
-        case SetComp_kind:
-            return "set comprehension";
-        case DictComp_kind:
-            return "dict comprehension";
-        case Dict_kind:
-            return "dict display";
-        case Set_kind:
-            return "set display";
-        case JoinedStr_kind:
-        case FormattedValue_kind:
-            return "f-string expression";
-        case Constant_kind: {
-            PyObject *value = e->v.Constant.value;
-            if (value == Py_None) {
-                return "None";
-            }
-            if (value == Py_False) {
-                return "False";
-            }
-            if (value == Py_True) {
-                return "True";
-            }
-            if (value == Py_Ellipsis) {
-                return "Ellipsis";
-            }
-            return "literal";
-        }
-        case Compare_kind:
-            return "comparison";
-        case IfExp_kind:
-            return "conditional expression";
-        case NamedExpr_kind:
-            return "named expression";
-        default:
-            PyErr_Format(PyExc_SystemError,
-                         "unexpected expression in assignment %d (line %d)",
-                         e->kind, e->lineno);
-            return NULL;
-    }
-}
-
-/* Set the context ctx for expr_ty e, recursively traversing e.
-
-   Only sets context for expr kinds that "can appear in assignment context"
-   (according to ../Parser/Python.asdl).  For other expr kinds, it sets
-   an appropriate syntax error and returns false.
-*/
-
-static int
-set_context(struct compiling *c, expr_ty e, expr_context_ty ctx, const node *n)
-{
-    asdl_seq *s = NULL;
-
-    /* Expressions in an augmented assignment have a Store context. */
-
-    switch (e->kind) {
-        case Attribute_kind:
-            e->v.Attribute.ctx = ctx;
-            if (ctx == Store && forbidden_name(c, e->v.Attribute.attr, n, 1))
-                return 0;
-            break;
-        case Subscript_kind:
-            e->v.Subscript.ctx = ctx;
-            break;
-        case Starred_kind:
-            e->v.Starred.ctx = ctx;
-            if (!set_context(c, e->v.Starred.value, ctx, n))
-                return 0;
-            break;
-        case Name_kind:
-            if (ctx == Store) {
-                if (forbidden_name(c, e->v.Name.id, n, 0))
-                    return 0; /* forbidden_name() calls ast_error() */
-            }
-            e->v.Name.ctx = ctx;
-            break;
-        case List_kind:
-            e->v.List.ctx = ctx;
-            s = e->v.List.elts;
-            break;
-        case Tuple_kind:
-            e->v.Tuple.ctx = ctx;
-            s = e->v.Tuple.elts;
-            break;
-        default: {
-            const char *expr_name = get_expr_name(e);
-            if (expr_name != NULL) {
-                ast_error(c, n, "cannot %s %s",
-                          ctx == Store ? "assign to" : "delete",
-                          expr_name);
-            }
-            return 0;
-        }
-    }
-
-    /* If the LHS is a list or tuple, we need to set the assignment
-       context for all the contained elements.
-    */
-    if (s) {
-        Py_ssize_t i;
-
-        for (i = 0; i < asdl_seq_LEN(s); i++) {
-            if (!set_context(c, (expr_ty)asdl_seq_GET(s, i), ctx, n))
-                return 0;
-        }
-    }
-    return 1;
-}
-
-static operator_ty
-ast_for_augassign(struct compiling *c, const node *n)
-{
-    REQ(n, augassign);
-    n = CHILD(n, 0);
-    switch (STR(n)[0]) {
-        case '+':
-            return Add;
-        case '-':
-            return Sub;
-        case '/':
-            if (STR(n)[1] == '/')
-                return FloorDiv;
-            else
-                return Div;
-        case '%':
-            return Mod;
-        case '<':
-            return LShift;
-        case '>':
-            return RShift;
-        case '&':
-            return BitAnd;
-        case '^':
-            return BitXor;
-        case '|':
-            return BitOr;
-        case '*':
-            if (STR(n)[1] == '*')
-                return Pow;
-            else
-                return Mult;
-        case '@':
-            if (c->c_feature_version < 5) {
-                ast_error(c, n,
-                          "The '@' operator is only supported in Python 3.5 and greater");
-                return (operator_ty)0;
-            }
-            return MatMult;
-        default:
-            PyErr_Format(PyExc_SystemError, "invalid augassign: %s", STR(n));
-            return (operator_ty)0;
-    }
-}
-
-static cmpop_ty
-ast_for_comp_op(struct compiling *c, const node *n)
-{
-    /* comp_op: '<'|'>'|'=='|'>='|'<='|'!='|'in'|'not' 'in'|'is'
-               |'is' 'not'
-    */
-    REQ(n, comp_op);
-    if (NCH(n) == 1) {
-        n = CHILD(n, 0);
-        switch (TYPE(n)) {
-            case LESS:
-                return Lt;
-            case GREATER:
-                return Gt;
-            case EQEQUAL:                       /* == */
-                return Eq;
-            case LESSEQUAL:
-                return LtE;
-            case GREATEREQUAL:
-                return GtE;
-            case NOTEQUAL:
-                return NotEq;
-            case NAME:
-                if (strcmp(STR(n), "in") == 0)
-                    return In;
-                if (strcmp(STR(n), "is") == 0)
-                    return Is;
-                /* fall through */
-            default:
-                PyErr_Format(PyExc_SystemError, "invalid comp_op: %s",
-                             STR(n));
-                return (cmpop_ty)0;
-        }
-    }
-    else if (NCH(n) == 2) {
-        /* handle "not in" and "is not" */
-        switch (TYPE(CHILD(n, 0))) {
-            case NAME:
-                if (strcmp(STR(CHILD(n, 1)), "in") == 0)
-                    return NotIn;
-                if (strcmp(STR(CHILD(n, 0)), "is") == 0)
-                    return IsNot;
-                /* fall through */
-            default:
-                PyErr_Format(PyExc_SystemError, "invalid comp_op: %s %s",
-                             STR(CHILD(n, 0)), STR(CHILD(n, 1)));
-                return (cmpop_ty)0;
-        }
-    }
-    PyErr_Format(PyExc_SystemError, "invalid comp_op: has %d children",
-                 NCH(n));
-    return (cmpop_ty)0;
-}
-
-static asdl_seq *
-seq_for_testlist(struct compiling *c, const node *n)
-{
-    /* testlist: test (',' test)* [',']
-       testlist_star_expr: test|star_expr (',' test|star_expr)* [',']
-    */
-    asdl_seq *seq;
-    expr_ty expression;
-    int i;
-    assert(TYPE(n) == testlist || TYPE(n) == testlist_star_expr || TYPE(n) == testlist_comp);
-
-    seq = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
-    if (!seq)
-        return NULL;
-
-    for (i = 0; i < NCH(n); i += 2) {
-        const node *ch = CHILD(n, i);
-        assert(TYPE(ch) == test || TYPE(ch) == test_nocond || TYPE(ch) == star_expr || TYPE(ch) == namedexpr_test);
-
-        expression = ast_for_expr(c, ch);
-        if (!expression)
-            return NULL;
-
-        assert(i / 2 < seq->size);
-        asdl_seq_SET(seq, i / 2, expression);
-    }
-    return seq;
-}
-
-static arg_ty
-ast_for_arg(struct compiling *c, const node *n)
-{
-    identifier name;
-    expr_ty annotation = NULL;
-    node *ch;
-    arg_ty ret;
-
-    assert(TYPE(n) == tfpdef || TYPE(n) == vfpdef);
-    ch = CHILD(n, 0);
-    name = NEW_IDENTIFIER(ch);
-    if (!name)
-        return NULL;
-    if (forbidden_name(c, name, ch, 0))
-        return NULL;
-
-    if (NCH(n) == 3 && TYPE(CHILD(n, 1)) == COLON) {
-        annotation = ast_for_expr(c, CHILD(n, 2));
-        if (!annotation)
-            return NULL;
-    }
-
-    ret = arg(name, annotation, NULL, LINENO(n), n->n_col_offset,
-              n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    if (!ret)
-        return NULL;
-    return ret;
-}
-
-/* returns -1 if failed to handle keyword only arguments
-   returns new position to keep processing if successful
-               (',' tfpdef ['=' test])*
-                     ^^^
-   start pointing here
- */
-static int
-handle_keywordonly_args(struct compiling *c, const node *n, int start,
-                        asdl_seq *kwonlyargs, asdl_seq *kwdefaults)
-{
-    PyObject *argname;
-    node *ch;
-    expr_ty expression, annotation;
-    arg_ty arg = NULL;
-    int i = start;
-    int j = 0; /* index for kwdefaults and kwonlyargs */
-
-    if (kwonlyargs == NULL) {
-        ast_error(c, CHILD(n, start), "named arguments must follow bare *");
-        return -1;
-    }
-    assert(kwdefaults != NULL);
-    while (i < NCH(n)) {
-        ch = CHILD(n, i);
-        switch (TYPE(ch)) {
-            case vfpdef:
-            case tfpdef:
-                if (i + 1 < NCH(n) && TYPE(CHILD(n, i + 1)) == EQUAL) {
-                    expression = ast_for_expr(c, CHILD(n, i + 2));
-                    if (!expression)
-                        goto error;
-                    asdl_seq_SET(kwdefaults, j, expression);
-                    i += 2; /* '=' and test */
-                }
-                else { /* setting NULL if no default value exists */
-                    asdl_seq_SET(kwdefaults, j, NULL);
-                }
-                if (NCH(ch) == 3) {
-                    /* ch is NAME ':' test */
-                    annotation = ast_for_expr(c, CHILD(ch, 2));
-                    if (!annotation)
-                        goto error;
-                }
-                else {
-                    annotation = NULL;
-                }
-                ch = CHILD(ch, 0);
-                argname = NEW_IDENTIFIER(ch);
-                if (!argname)
-                    goto error;
-                if (forbidden_name(c, argname, ch, 0))
-                    goto error;
-                arg = arg(argname, annotation, NULL, LINENO(ch), ch->n_col_offset,
-                          ch->n_end_lineno, ch->n_end_col_offset,
-                          c->c_arena);
-                if (!arg)
-                    goto error;
-                asdl_seq_SET(kwonlyargs, j++, arg);
-                i += 1; /* the name */
-                if (i < NCH(n) && TYPE(CHILD(n, i)) == COMMA)
-                    i += 1; /* the comma, if present */
-                break;
-            case TYPE_COMMENT:
-                /* arg will be equal to the last argument processed */
-                arg->type_comment = NEW_TYPE_COMMENT(ch);
-                if (!arg->type_comment)
-                    goto error;
-                i += 1;
-                break;
-            case DOUBLESTAR:
-                return i;
-            default:
-                ast_error(c, ch, "unexpected node");
-                goto error;
-        }
-    }
-    return i;
- error:
-    return -1;
-}
-
-/* Create AST for argument list. */
-
-static arguments_ty
-ast_for_arguments(struct compiling *c, const node *n)
-{
-    /* This function handles both typedargslist (function definition)
-       and varargslist (lambda definition).
-
-       parameters: '(' [typedargslist] ')'
-
-       The following definition for typedarglist is equivalent to this set of rules:
-
-         arguments = argument (',' [TYPE_COMMENT] argument)*
-         argument = tfpdef ['=' test]
-         kwargs = '**' tfpdef [','] [TYPE_COMMENT]
-         args = '*' [tfpdef]
-         kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT | [','
-                         [TYPE_COMMENT] [kwargs]])
-         args_kwonly_kwargs = args kwonly_kwargs | kwargs
-         poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT | [','
-                                         [TYPE_COMMENT] [args_kwonly_kwargs]])
-         typedargslist_no_posonly  = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
-         typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT]
-                        typedargslist_no_posonly]])|(typedargslist_no_posonly)"
-
-       typedargslist: ( (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])*
-           ',' [TYPE_COMMENT] '/' [',' [ [TYPE_COMMENT] tfpdef ['=' test] ( ','
-           [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [ '*'
-           [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [','
-           [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) | '**' tfpdef [',']
-           [TYPE_COMMENT]]]) | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])*
-           (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) |
-           '**' tfpdef [','] [TYPE_COMMENT]]] ) |  (tfpdef ['=' test] (','
-           [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [ '*'
-           [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [','
-           [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) | '**' tfpdef [',']
-           [TYPE_COMMENT]]]) | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])*
-           (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]]) |
-           '**' tfpdef [','] [TYPE_COMMENT]))
-
-       tfpdef: NAME [':' test]
-
-       The following definition for varargslist is equivalent to this set of rules:
-
-         arguments = argument (',' argument )*
-         argument = vfpdef ['=' test]
-         kwargs = '**' vfpdef [',']
-         args = '*' [vfpdef]
-         kwonly_kwargs = (',' argument )* [',' [kwargs]]
-         args_kwonly_kwargs = args kwonly_kwargs | kwargs
-         poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]]
-         vararglist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
-         varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] |
-                       (vararglist_no_posonly)
-
-       varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['='
-           test] (',' vfpdef ['=' test])* [',' [ '*' [vfpdef] (',' vfpdef ['=' test])* [','
-           ['**' vfpdef [',']]] | '**' vfpdef [',']]] | '*' [vfpdef] (',' vfpdef ['=' test])*
-           [',' ['**' vfpdef [',']]] | '**' vfpdef [',']) ]] | (vfpdef ['=' test] (',' vfpdef
-           ['=' test])* [',' [ '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
-           | '**' vfpdef [',']]] | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef
-           [',']]] | '**' vfpdef [','])
-
-       vfpdef: NAME
-
-    */
-    int i, j, k, l, nposonlyargs=0, nposargs = 0, nkwonlyargs = 0;
-    int nposdefaults = 0, found_default = 0;
-    asdl_seq *posonlyargs, *posargs, *posdefaults, *kwonlyargs, *kwdefaults;
-    arg_ty vararg = NULL, kwarg = NULL;
-    arg_ty arg = NULL;
-    node *ch;
-
-    if (TYPE(n) == parameters) {
-        if (NCH(n) == 2) /* () as argument list */
-            return arguments(NULL, NULL, NULL, NULL, NULL, NULL, NULL, c->c_arena);
-        n = CHILD(n, 1);
-    }
-    assert(TYPE(n) == typedargslist || TYPE(n) == varargslist);
-
-    /* First count the number of positional args & defaults.  The
-       variable i is the loop index for this for loop and the next.
-       The next loop picks up where the first leaves off.
-    */
-    for (i = 0; i < NCH(n); i++) {
-        ch = CHILD(n, i);
-        if (TYPE(ch) == STAR) {
-            /* skip star */
-            i++;
-            if (i < NCH(n) && /* skip argument following star */
-                (TYPE(CHILD(n, i)) == tfpdef ||
-                 TYPE(CHILD(n, i)) == vfpdef)) {
-                i++;
-            }
-            break;
-        }
-        if (TYPE(ch) == DOUBLESTAR) break;
-        if (TYPE(ch) == vfpdef || TYPE(ch) == tfpdef) nposargs++;
-        if (TYPE(ch) == EQUAL) nposdefaults++;
-        if (TYPE(ch) == SLASH ) {
-            nposonlyargs = nposargs;
-            nposargs = 0;
-        }
-    }
-    /* count the number of keyword only args &
-       defaults for keyword only args */
-    for ( ; i < NCH(n); ++i) {
-        ch = CHILD(n, i);
-        if (TYPE(ch) == DOUBLESTAR) break;
-        if (TYPE(ch) == tfpdef || TYPE(ch) == vfpdef) nkwonlyargs++;
-    }
-    posonlyargs = (nposonlyargs ? _Py_asdl_seq_new(nposonlyargs, c->c_arena) : NULL);
-    if (!posonlyargs && nposonlyargs) {
-        return NULL;
-    }
-    posargs = (nposargs ? _Py_asdl_seq_new(nposargs, c->c_arena) : NULL);
-    if (!posargs && nposargs)
-        return NULL;
-    kwonlyargs = (nkwonlyargs ?
-                   _Py_asdl_seq_new(nkwonlyargs, c->c_arena) : NULL);
-    if (!kwonlyargs && nkwonlyargs)
-        return NULL;
-    posdefaults = (nposdefaults ?
-                    _Py_asdl_seq_new(nposdefaults, c->c_arena) : NULL);
-    if (!posdefaults && nposdefaults)
-        return NULL;
-    /* The length of kwonlyargs and kwdefaults are same
-       since we set NULL as default for keyword only argument w/o default
-       - we have sequence data structure, but no dictionary */
-    kwdefaults = (nkwonlyargs ?
-                   _Py_asdl_seq_new(nkwonlyargs, c->c_arena) : NULL);
-    if (!kwdefaults && nkwonlyargs)
-        return NULL;
-
-    /* tfpdef: NAME [':' test]
-       vfpdef: NAME
-    */
-    i = 0;
-    j = 0;  /* index for defaults */
-    k = 0;  /* index for args */
-    l = 0;  /* index for posonlyargs */
-    while (i < NCH(n)) {
-        ch = CHILD(n, i);
-        switch (TYPE(ch)) {
-            case tfpdef:
-            case vfpdef:
-                /* XXX Need to worry about checking if TYPE(CHILD(n, i+1)) is
-                   anything other than EQUAL or a comma? */
-                /* XXX Should NCH(n) check be made a separate check? */
-                if (i + 1 < NCH(n) && TYPE(CHILD(n, i + 1)) == EQUAL) {
-                    expr_ty expression = ast_for_expr(c, CHILD(n, i + 2));
-                    if (!expression)
-                        return NULL;
-                    assert(posdefaults != NULL);
-                    asdl_seq_SET(posdefaults, j++, expression);
-                    i += 2;
-                    found_default = 1;
-                }
-                else if (found_default) {
-                    ast_error(c, n,
-                              "non-default argument follows default argument");
-                    return NULL;
-                }
-                arg = ast_for_arg(c, ch);
-                if (!arg)
-                    return NULL;
-                if (l < nposonlyargs) {
-                    asdl_seq_SET(posonlyargs, l++, arg);
-                } else {
-                    asdl_seq_SET(posargs, k++, arg);
-                }
-                i += 1; /* the name */
-                if (i < NCH(n) && TYPE(CHILD(n, i)) == COMMA)
-                    i += 1; /* the comma, if present */
-                break;
-             case SLASH:
-                /* Advance the slash and the comma. If there are more names
-                 * after the slash there will be a comma so we are advancing
-                 * the correct number of nodes. If the slash is the last item,
-                 * we will be advancing an extra token but then * i > NCH(n)
-                 * and the enclosing while will finish correctly. */
-                i += 2;
-                break;
-            case STAR:
-                if (i+1 >= NCH(n) ||
-                    (i+2 == NCH(n) && (TYPE(CHILD(n, i+1)) == COMMA
-                                       || TYPE(CHILD(n, i+1)) == TYPE_COMMENT))) {
-                    ast_error(c, CHILD(n, i),
-                              "named arguments must follow bare *");
-                    return NULL;
-                }
-                ch = CHILD(n, i+1);  /* tfpdef or COMMA */
-                if (TYPE(ch) == COMMA) {
-                    int res = 0;
-                    i += 2; /* now follows keyword only arguments */
-
-                    if (i < NCH(n) && TYPE(CHILD(n, i)) == TYPE_COMMENT) {
-                        ast_error(c, CHILD(n, i),
-                                  "bare * has associated type comment");
-                        return NULL;
-                    }
-
-                    res = handle_keywordonly_args(c, n, i,
-                                                  kwonlyargs, kwdefaults);
-                    if (res == -1) return NULL;
-                    i = res; /* res has new position to process */
-                }
-                else {
-                    vararg = ast_for_arg(c, ch);
-                    if (!vararg)
-                        return NULL;
-
-                i += 2; /* the star and the name */
-                if (i < NCH(n) && TYPE(CHILD(n, i)) == COMMA)
-                    i += 1; /* the comma, if present */
-
-                if (i < NCH(n) && TYPE(CHILD(n, i)) == TYPE_COMMENT) {
-                        vararg->type_comment = NEW_TYPE_COMMENT(CHILD(n, i));
-                        if (!vararg->type_comment)
-                            return NULL;
-                        i += 1;
-                    }
-
-                    if (i < NCH(n) && (TYPE(CHILD(n, i)) == tfpdef
-                                    || TYPE(CHILD(n, i)) == vfpdef)) {
-                        int res = 0;
-                        res = handle_keywordonly_args(c, n, i,
-                                                      kwonlyargs, kwdefaults);
-                        if (res == -1) return NULL;
-                        i = res; /* res has new position to process */
-                    }
-                }
-                break;
-            case DOUBLESTAR:
-                ch = CHILD(n, i+1);  /* tfpdef */
-                assert(TYPE(ch) == tfpdef || TYPE(ch) == vfpdef);
-                kwarg = ast_for_arg(c, ch);
-                if (!kwarg)
-                    return NULL;
-                i += 2; /* the double star and the name */
-                if (i < NCH(n) && TYPE(CHILD(n, i)) == COMMA)
-                    i += 1; /* the comma, if present */
-                break;
-            case TYPE_COMMENT:
-                assert(i);
-
-                if (kwarg)
-                    arg = kwarg;
-
-                /* arg will be equal to the last argument processed */
-                arg->type_comment = NEW_TYPE_COMMENT(ch);
-                if (!arg->type_comment)
-                    return NULL;
-                i += 1;
-                break;
-            default:
-                PyErr_Format(PyExc_SystemError,
-                             "unexpected node in varargslist: %d @ %d",
-                             TYPE(ch), i);
-                return NULL;
-        }
-    }
-    return arguments(posonlyargs, posargs, vararg, kwonlyargs, kwdefaults, kwarg, posdefaults, c->c_arena);
-}
-
-static expr_ty
-ast_for_decorator(struct compiling *c, const node *n)
-{
-    /* decorator: '@' namedexpr_test NEWLINE */
-
-    REQ(n, decorator);
-    REQ(CHILD(n, 0), AT);
-    REQ(CHILD(n, 2), NEWLINE);
-
-    return ast_for_expr(c, CHILD(n, 1));
-}
-
-static asdl_seq*
-ast_for_decorators(struct compiling *c, const node *n)
-{
-    asdl_seq* decorator_seq;
-    expr_ty d;
-    int i;
-
-    REQ(n, decorators);
-    decorator_seq = _Py_asdl_seq_new(NCH(n), c->c_arena);
-    if (!decorator_seq)
-        return NULL;
-
-    for (i = 0; i < NCH(n); i++) {
-        d = ast_for_decorator(c, CHILD(n, i));
-        if (!d)
-            return NULL;
-        asdl_seq_SET(decorator_seq, i, d);
-    }
-    return decorator_seq;
-}
-
-static stmt_ty
-ast_for_funcdef_impl(struct compiling *c, const node *n0,
-                     asdl_seq *decorator_seq, bool is_async)
-{
-    /* funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT] suite */
-    const node * const n = is_async ? CHILD(n0, 1) : n0;
-    identifier name;
-    arguments_ty args;
-    asdl_seq *body;
-    expr_ty returns = NULL;
-    int name_i = 1;
-    int end_lineno, end_col_offset;
-    node *tc;
-    string type_comment = NULL;
-
-    if (is_async && c->c_feature_version < 5) {
-        ast_error(c, n,
-                  "Async functions are only supported in Python 3.5 and greater");
-        return NULL;
-    }
-
-    REQ(n, funcdef);
-
-    name = NEW_IDENTIFIER(CHILD(n, name_i));
-    if (!name)
-        return NULL;
-    if (forbidden_name(c, name, CHILD(n, name_i), 0))
-        return NULL;
-    args = ast_for_arguments(c, CHILD(n, name_i + 1));
-    if (!args)
-        return NULL;
-    if (TYPE(CHILD(n, name_i+2)) == RARROW) {
-        returns = ast_for_expr(c, CHILD(n, name_i + 3));
-        if (!returns)
-            return NULL;
-        name_i += 2;
-    }
-    if (TYPE(CHILD(n, name_i + 3)) == TYPE_COMMENT) {
-        type_comment = NEW_TYPE_COMMENT(CHILD(n, name_i + 3));
-        if (!type_comment)
-            return NULL;
-        name_i += 1;
-    }
-    body = ast_for_suite(c, CHILD(n, name_i + 3));
-    if (!body)
-        return NULL;
-    get_last_end_pos(body, &end_lineno, &end_col_offset);
-
-    if (NCH(CHILD(n, name_i + 3)) > 1) {
-        /* Check if the suite has a type comment in it. */
-        tc = CHILD(CHILD(n, name_i + 3), 1);
-
-        if (TYPE(tc) == TYPE_COMMENT) {
-            if (type_comment != NULL) {
-                ast_error(c, n, "Cannot have two type comments on def");
-                return NULL;
-            }
-            type_comment = NEW_TYPE_COMMENT(tc);
-            if (!type_comment)
-                return NULL;
-        }
-    }
-
-    if (is_async)
-        return AsyncFunctionDef(name, args, body, decorator_seq, returns, type_comment,
-                                LINENO(n0), n0->n_col_offset, end_lineno, end_col_offset, c->c_arena);
-    else
-        return FunctionDef(name, args, body, decorator_seq, returns, type_comment,
-                           LINENO(n), n->n_col_offset, end_lineno, end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_async_funcdef(struct compiling *c, const node *n, asdl_seq *decorator_seq)
-{
-    /* async_funcdef: ASYNC funcdef */
-    REQ(n, async_funcdef);
-    REQ(CHILD(n, 0), ASYNC);
-    REQ(CHILD(n, 1), funcdef);
-
-    return ast_for_funcdef_impl(c, n, decorator_seq,
-                                true /* is_async */);
-}
-
-static stmt_ty
-ast_for_funcdef(struct compiling *c, const node *n, asdl_seq *decorator_seq)
-{
-    /* funcdef: 'def' NAME parameters ['->' test] ':' suite */
-    return ast_for_funcdef_impl(c, n, decorator_seq,
-                                false /* is_async */);
-}
-
-
-static stmt_ty
-ast_for_async_stmt(struct compiling *c, const node *n)
-{
-    /* async_stmt: ASYNC (funcdef | with_stmt | for_stmt) */
-    REQ(n, async_stmt);
-    REQ(CHILD(n, 0), ASYNC);
-
-    switch (TYPE(CHILD(n, 1))) {
-        case funcdef:
-            return ast_for_funcdef_impl(c, n, NULL,
-                                        true /* is_async */);
-        case with_stmt:
-            return ast_for_with_stmt(c, n,
-                                     true /* is_async */);
-
-        case for_stmt:
-            return ast_for_for_stmt(c, n,
-                                    true /* is_async */);
-
-        default:
-            PyErr_Format(PyExc_SystemError,
-                         "invalid async stament: %s",
-                         STR(CHILD(n, 1)));
-            return NULL;
-    }
-}
-
-static stmt_ty
-ast_for_decorated(struct compiling *c, const node *n)
-{
-    /* decorated: decorators (classdef | funcdef | async_funcdef) */
-    stmt_ty thing = NULL;
-    asdl_seq *decorator_seq = NULL;
-
-    REQ(n, decorated);
-
-    decorator_seq = ast_for_decorators(c, CHILD(n, 0));
-    if (!decorator_seq)
-      return NULL;
-
-    assert(TYPE(CHILD(n, 1)) == funcdef ||
-           TYPE(CHILD(n, 1)) == async_funcdef ||
-           TYPE(CHILD(n, 1)) == classdef);
-
-    if (TYPE(CHILD(n, 1)) == funcdef) {
-      thing = ast_for_funcdef(c, CHILD(n, 1), decorator_seq);
-    } else if (TYPE(CHILD(n, 1)) == classdef) {
-      thing = ast_for_classdef(c, CHILD(n, 1), decorator_seq);
-    } else if (TYPE(CHILD(n, 1)) == async_funcdef) {
-      thing = ast_for_async_funcdef(c, CHILD(n, 1), decorator_seq);
-    }
-    return thing;
-}
-
-static expr_ty
-ast_for_namedexpr(struct compiling *c, const node *n)
-{
-    /* namedexpr_test: test [':=' test]
-       argument: ( test [comp_for] |
-            test ':=' test |
-            test '=' test |
-            '**' test |
-            '*' test )
-    */
-    expr_ty target, value;
-
-    target = ast_for_expr(c, CHILD(n, 0));
-    if (!target)
-        return NULL;
-
-    value = ast_for_expr(c, CHILD(n, 2));
-    if (!value)
-        return NULL;
-
-    if (target->kind != Name_kind) {
-        const char *expr_name = get_expr_name(target);
-        if (expr_name != NULL) {
-            ast_error(c, n, "cannot use assignment expressions with %s", expr_name);
-        }
-        return NULL;
-    }
-
-    if (!set_context(c, target, Store, n))
-        return NULL;
-
-    return NamedExpr(target, value, LINENO(n), n->n_col_offset, n->n_end_lineno,
-                     n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_lambdef(struct compiling *c, const node *n)
-{
-    /* lambdef: 'lambda' [varargslist] ':' test
-       lambdef_nocond: 'lambda' [varargslist] ':' test_nocond */
-    arguments_ty args;
-    expr_ty expression;
-
-    if (NCH(n) == 3) {
-        args = arguments(NULL, NULL, NULL, NULL, NULL, NULL, NULL, c->c_arena);
-        if (!args)
-            return NULL;
-        expression = ast_for_expr(c, CHILD(n, 2));
-        if (!expression)
-            return NULL;
-    }
-    else {
-        args = ast_for_arguments(c, CHILD(n, 1));
-        if (!args)
-            return NULL;
-        expression = ast_for_expr(c, CHILD(n, 3));
-        if (!expression)
-            return NULL;
-    }
-
-    return Lambda(args, expression, LINENO(n), n->n_col_offset,
-                  n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_ifexpr(struct compiling *c, const node *n)
-{
-    /* test: or_test 'if' or_test 'else' test */
-    expr_ty expression, body, orelse;
-
-    assert(NCH(n) == 5);
-    body = ast_for_expr(c, CHILD(n, 0));
-    if (!body)
-        return NULL;
-    expression = ast_for_expr(c, CHILD(n, 2));
-    if (!expression)
-        return NULL;
-    orelse = ast_for_expr(c, CHILD(n, 4));
-    if (!orelse)
-        return NULL;
-    return IfExp(expression, body, orelse, LINENO(n), n->n_col_offset,
-                 n->n_end_lineno, n->n_end_col_offset,
-                 c->c_arena);
-}
-
-/*
-   Count the number of 'for' loops in a comprehension.
-
-   Helper for ast_for_comprehension().
-*/
-
-static int
-count_comp_fors(struct compiling *c, const node *n)
-{
-    int n_fors = 0;
-
-  count_comp_for:
-    n_fors++;
-    REQ(n, comp_for);
-    if (NCH(n) == 2) {
-        REQ(CHILD(n, 0), ASYNC);
-        n = CHILD(n, 1);
-    }
-    else if (NCH(n) == 1) {
-        n = CHILD(n, 0);
-    }
-    else {
-        goto error;
-    }
-    if (NCH(n) == (5)) {
-        n = CHILD(n, 4);
-    }
-    else {
-        return n_fors;
-    }
-  count_comp_iter:
-    REQ(n, comp_iter);
-    n = CHILD(n, 0);
-    if (TYPE(n) == comp_for)
-        goto count_comp_for;
-    else if (TYPE(n) == comp_if) {
-        if (NCH(n) == 3) {
-            n = CHILD(n, 2);
-            goto count_comp_iter;
-        }
-        else
-            return n_fors;
-    }
-
-  error:
-    /* Should never be reached */
-    PyErr_SetString(PyExc_SystemError,
-                    "logic error in count_comp_fors");
-    return -1;
-}
-
-/* Count the number of 'if' statements in a comprehension.
-
-   Helper for ast_for_comprehension().
-*/
-
-static int
-count_comp_ifs(struct compiling *c, const node *n)
-{
-    int n_ifs = 0;
-
-    while (1) {
-        REQ(n, comp_iter);
-        if (TYPE(CHILD(n, 0)) == comp_for)
-            return n_ifs;
-        n = CHILD(n, 0);
-        REQ(n, comp_if);
-        n_ifs++;
-        if (NCH(n) == 2)
-            return n_ifs;
-        n = CHILD(n, 2);
-    }
-}
-
-static asdl_seq *
-ast_for_comprehension(struct compiling *c, const node *n)
-{
-    int i, n_fors;
-    asdl_seq *comps;
-
-    n_fors = count_comp_fors(c, n);
-    if (n_fors == -1)
-        return NULL;
-
-    comps = _Py_asdl_seq_new(n_fors, c->c_arena);
-    if (!comps)
-        return NULL;
-
-    for (i = 0; i < n_fors; i++) {
-        comprehension_ty comp;
-        asdl_seq *t;
-        expr_ty expression, first;
-        node *for_ch;
-        node *sync_n;
-        int is_async = 0;
-
-        REQ(n, comp_for);
-
-        if (NCH(n) == 2) {
-            is_async = 1;
-            REQ(CHILD(n, 0), ASYNC);
-            sync_n = CHILD(n, 1);
-        }
-        else {
-            sync_n = CHILD(n, 0);
-        }
-        REQ(sync_n, sync_comp_for);
-
-        /* Async comprehensions only allowed in Python 3.6 and greater */
-        if (is_async && c->c_feature_version < 6) {
-            ast_error(c, n,
-                      "Async comprehensions are only supported in Python 3.6 and greater");
-            return NULL;
-        }
-
-        for_ch = CHILD(sync_n, 1);
-        t = ast_for_exprlist(c, for_ch, Store);
-        if (!t)
-            return NULL;
-        expression = ast_for_expr(c, CHILD(sync_n, 3));
-        if (!expression)
-            return NULL;
-
-        /* Check the # of children rather than the length of t, since
-           (x for x, in ...) has 1 element in t, but still requires a Tuple. */
-        first = (expr_ty)asdl_seq_GET(t, 0);
-        if (NCH(for_ch) == 1)
-            comp = comprehension(first, expression, NULL,
-                                 is_async, c->c_arena);
-        else
-            comp = comprehension(Tuple(t, Store, first->lineno, first->col_offset,
-                                       for_ch->n_end_lineno, for_ch->n_end_col_offset,
-                                       c->c_arena),
-                                 expression, NULL, is_async, c->c_arena);
-        if (!comp)
-            return NULL;
-
-        if (NCH(sync_n) == 5) {
-            int j, n_ifs;
-            asdl_seq *ifs;
-
-            n = CHILD(sync_n, 4);
-            n_ifs = count_comp_ifs(c, n);
-            if (n_ifs == -1)
-                return NULL;
-
-            ifs = _Py_asdl_seq_new(n_ifs, c->c_arena);
-            if (!ifs)
-                return NULL;
-
-            for (j = 0; j < n_ifs; j++) {
-                REQ(n, comp_iter);
-                n = CHILD(n, 0);
-                REQ(n, comp_if);
-
-                expression = ast_for_expr(c, CHILD(n, 1));
-                if (!expression)
-                    return NULL;
-                asdl_seq_SET(ifs, j, expression);
-                if (NCH(n) == 3)
-                    n = CHILD(n, 2);
-            }
-            /* on exit, must guarantee that n is a comp_for */
-            if (TYPE(n) == comp_iter)
-                n = CHILD(n, 0);
-            comp->ifs = ifs;
-        }
-        asdl_seq_SET(comps, i, comp);
-    }
-    return comps;
-}
-
-static expr_ty
-ast_for_itercomp(struct compiling *c, const node *n, int type)
-{
-    /* testlist_comp: (test|star_expr)
-     *                ( comp_for | (',' (test|star_expr))* [','] ) */
-    expr_ty elt;
-    asdl_seq *comps;
-    node *ch;
-
-    assert(NCH(n) > 1);
-
-    ch = CHILD(n, 0);
-    elt = ast_for_expr(c, ch);
-    if (!elt)
-        return NULL;
-    if (elt->kind == Starred_kind) {
-        ast_error(c, ch, "iterable unpacking cannot be used in comprehension");
-        return NULL;
-    }
-
-    comps = ast_for_comprehension(c, CHILD(n, 1));
-    if (!comps)
-        return NULL;
-
-    if (type == COMP_GENEXP)
-        return GeneratorExp(elt, comps, LINENO(n), n->n_col_offset,
-                            n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    else if (type == COMP_LISTCOMP)
-        return ListComp(elt, comps, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    else if (type == COMP_SETCOMP)
-        return SetComp(elt, comps, LINENO(n), n->n_col_offset,
-                       n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    else
-        /* Should never happen */
-        return NULL;
-}
-
-/* Fills in the key, value pair corresponding to the dict element.  In case
- * of an unpacking, key is NULL.  *i is advanced by the number of ast
- * elements.  Iff successful, nonzero is returned.
- */
-static int
-ast_for_dictelement(struct compiling *c, const node *n, int *i,
-                    expr_ty *key, expr_ty *value)
-{
-    expr_ty expression;
-    if (TYPE(CHILD(n, *i)) == DOUBLESTAR) {
-        assert(NCH(n) - *i >= 2);
-
-        expression = ast_for_expr(c, CHILD(n, *i + 1));
-        if (!expression)
-            return 0;
-        *key = NULL;
-        *value = expression;
-
-        *i += 2;
-    }
-    else {
-        assert(NCH(n) - *i >= 3);
-
-        expression = ast_for_expr(c, CHILD(n, *i));
-        if (!expression)
-            return 0;
-        *key = expression;
-
-        REQ(CHILD(n, *i + 1), COLON);
-
-        expression = ast_for_expr(c, CHILD(n, *i + 2));
-        if (!expression)
-            return 0;
-        *value = expression;
-
-        *i += 3;
-    }
-    return 1;
-}
-
-static expr_ty
-ast_for_dictcomp(struct compiling *c, const node *n)
-{
-    expr_ty key, value;
-    asdl_seq *comps;
-    int i = 0;
-
-    if (!ast_for_dictelement(c, n, &i, &key, &value))
-        return NULL;
-    assert(key);
-    assert(NCH(n) - i >= 1);
-
-    comps = ast_for_comprehension(c, CHILD(n, i));
-    if (!comps)
-        return NULL;
-
-    return DictComp(key, value, comps, LINENO(n), n->n_col_offset,
-                    n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_dictdisplay(struct compiling *c, const node *n)
-{
-    int i;
-    int j;
-    int size;
-    asdl_seq *keys, *values;
-
-    size = (NCH(n) + 1) / 3; /* +1 in case no trailing comma */
-    keys = _Py_asdl_seq_new(size, c->c_arena);
-    if (!keys)
-        return NULL;
-
-    values = _Py_asdl_seq_new(size, c->c_arena);
-    if (!values)
-        return NULL;
-
-    j = 0;
-    for (i = 0; i < NCH(n); i++) {
-        expr_ty key, value;
-
-        if (!ast_for_dictelement(c, n, &i, &key, &value))
-            return NULL;
-        asdl_seq_SET(keys, j, key);
-        asdl_seq_SET(values, j, value);
-
-        j++;
-    }
-    keys->size = j;
-    values->size = j;
-    return Dict(keys, values, LINENO(n), n->n_col_offset,
-                n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_genexp(struct compiling *c, const node *n)
-{
-    assert(TYPE(n) == (testlist_comp) || TYPE(n) == (argument));
-    return ast_for_itercomp(c, n, COMP_GENEXP);
-}
-
-static expr_ty
-ast_for_listcomp(struct compiling *c, const node *n)
-{
-    assert(TYPE(n) == (testlist_comp));
-    return ast_for_itercomp(c, n, COMP_LISTCOMP);
-}
-
-static expr_ty
-ast_for_setcomp(struct compiling *c, const node *n)
-{
-    assert(TYPE(n) == (dictorsetmaker));
-    return ast_for_itercomp(c, n, COMP_SETCOMP);
-}
-
-static expr_ty
-ast_for_setdisplay(struct compiling *c, const node *n)
-{
-    int i;
-    int size;
-    asdl_seq *elts;
-
-    assert(TYPE(n) == (dictorsetmaker));
-    size = (NCH(n) + 1) / 2; /* +1 in case no trailing comma */
-    elts = _Py_asdl_seq_new(size, c->c_arena);
-    if (!elts)
-        return NULL;
-    for (i = 0; i < NCH(n); i += 2) {
-        expr_ty expression;
-        expression = ast_for_expr(c, CHILD(n, i));
-        if (!expression)
-            return NULL;
-        asdl_seq_SET(elts, i / 2, expression);
-    }
-    return Set(elts, LINENO(n), n->n_col_offset,
-               n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_atom(struct compiling *c, const node *n)
-{
-    /* atom: '(' [yield_expr|testlist_comp] ')' | '[' [testlist_comp] ']'
-       | '{' [dictmaker|testlist_comp] '}' | NAME | NUMBER | STRING+
-       | '...' | 'None' | 'True' | 'False'
-    */
-    node *ch = CHILD(n, 0);
-
-    switch (TYPE(ch)) {
-    case NAME: {
-        PyObject *name;
-        const char *s = STR(ch);
-        size_t len = strlen(s);
-        if (len >= 4 && len <= 5) {
-            if (!strcmp(s, "None"))
-                return Constant(Py_None, NULL, LINENO(n), n->n_col_offset,
-                                n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            if (!strcmp(s, "True"))
-                return Constant(Py_True, NULL, LINENO(n), n->n_col_offset,
-                                n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            if (!strcmp(s, "False"))
-                return Constant(Py_False, NULL, LINENO(n), n->n_col_offset,
-                                n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        name = new_identifier(s, c);
-        if (!name)
-            return NULL;
-        /* All names start in Load context, but may later be changed. */
-        return Name(name, Load, LINENO(n), n->n_col_offset,
-                    n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    case STRING: {
-        expr_ty str = parsestrplus(c, n);
-        if (!str) {
-            const char *errtype = NULL;
-            if (PyErr_ExceptionMatches(PyExc_UnicodeError))
-                errtype = "unicode error";
-            else if (PyErr_ExceptionMatches(PyExc_ValueError))
-                errtype = "value error";
-            if (errtype) {
-                PyObject *type, *value, *tback, *errstr;
-                PyErr_Fetch(&type, &value, &tback);
-                errstr = PyObject_Str(value);
-                if (errstr) {
-                    ast_error(c, n, "(%s) %U", errtype, errstr);
-                    Py_DECREF(errstr);
-                }
-                else {
-                    PyErr_Clear();
-                    ast_error(c, n, "(%s) unknown error", errtype);
-                }
-                Py_DECREF(type);
-                Py_XDECREF(value);
-                Py_XDECREF(tback);
-            }
-            return NULL;
-        }
-        return str;
-    }
-    case NUMBER: {
-        PyObject *pynum;
-        /* Underscores in numeric literals are only allowed in Python 3.6 or greater */
-        /* Check for underscores here rather than in parse_number so we can report a line number on error */
-        if (c->c_feature_version < 6 && strchr(STR(ch), '_') != NULL) {
-            ast_error(c, ch,
-                      "Underscores in numeric literals are only supported in Python 3.6 and greater");
-            return NULL;
-        }
-        pynum = parsenumber(c, STR(ch));
-        if (!pynum)
-            return NULL;
-
-        if (PyArena_AddPyObject(c->c_arena, pynum) < 0) {
-            Py_DECREF(pynum);
-            return NULL;
-        }
-        return Constant(pynum, NULL, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    case ELLIPSIS: /* Ellipsis */
-        return Constant(Py_Ellipsis, NULL, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    case LPAR: /* some parenthesized expressions */
-        ch = CHILD(n, 1);
-
-        if (TYPE(ch) == RPAR)
-            return Tuple(NULL, Load, LINENO(n), n->n_col_offset,
-                         n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-
-        if (TYPE(ch) == yield_expr)
-            return ast_for_expr(c, ch);
-
-        /* testlist_comp: test ( comp_for | (',' test)* [','] ) */
-        if (NCH(ch) == 1) {
-            return ast_for_testlist(c, ch);
-        }
-
-        if (TYPE(CHILD(ch, 1)) == comp_for) {
-            return copy_location(ast_for_genexp(c, ch), n, n);
-        }
-        else {
-            return copy_location(ast_for_testlist(c, ch), n, n);
-        }
-    case LSQB: /* list (or list comprehension) */
-        ch = CHILD(n, 1);
-
-        if (TYPE(ch) == RSQB)
-            return List(NULL, Load, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-
-        REQ(ch, testlist_comp);
-        if (NCH(ch) == 1 || TYPE(CHILD(ch, 1)) == COMMA) {
-            asdl_seq *elts = seq_for_testlist(c, ch);
-            if (!elts)
-                return NULL;
-
-            return List(elts, Load, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        else {
-            return copy_location(ast_for_listcomp(c, ch), n, n);
-        }
-    case LBRACE: {
-        /* dictorsetmaker: ( ((test ':' test | '**' test)
-         *                    (comp_for | (',' (test ':' test | '**' test))* [','])) |
-         *                   ((test | '*' test)
-         *                    (comp_for | (',' (test | '*' test))* [','])) ) */
-        expr_ty res;
-        ch = CHILD(n, 1);
-        if (TYPE(ch) == RBRACE) {
-            /* It's an empty dict. */
-            return Dict(NULL, NULL, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        else {
-            int is_dict = (TYPE(CHILD(ch, 0)) == DOUBLESTAR);
-            if (NCH(ch) == 1 ||
-                    (NCH(ch) > 1 &&
-                     TYPE(CHILD(ch, 1)) == COMMA)) {
-                /* It's a set display. */
-                res = ast_for_setdisplay(c, ch);
-            }
-            else if (NCH(ch) > 1 &&
-                    TYPE(CHILD(ch, 1)) == comp_for) {
-                /* It's a set comprehension. */
-                res = ast_for_setcomp(c, ch);
-            }
-            else if (NCH(ch) > 3 - is_dict &&
-                    TYPE(CHILD(ch, 3 - is_dict)) == comp_for) {
-                /* It's a dictionary comprehension. */
-                if (is_dict) {
-                    ast_error(c, n,
-                              "dict unpacking cannot be used in dict comprehension");
-                    return NULL;
-                }
-                res = ast_for_dictcomp(c, ch);
-            }
-            else {
-                /* It's a dictionary display. */
-                res = ast_for_dictdisplay(c, ch);
-            }
-            return copy_location(res, n, n);
-        }
-    }
-    default:
-        PyErr_Format(PyExc_SystemError, "unhandled atom %d", TYPE(ch));
-        return NULL;
-    }
-}
-
-static expr_ty
-ast_for_slice(struct compiling *c, const node *n)
-{
-    node *ch;
-    expr_ty lower = NULL, upper = NULL, step = NULL;
-
-    REQ(n, subscript);
-
-    /*
-       subscript: test | [test] ':' [test] [sliceop]
-       sliceop: ':' [test]
-    */
-    ch = CHILD(n, 0);
-    if (NCH(n) == 1 && TYPE(ch) == test) {
-        return ast_for_expr(c, ch);
-    }
-
-    if (TYPE(ch) == test) {
-        lower = ast_for_expr(c, ch);
-        if (!lower)
-            return NULL;
-    }
-
-    /* If there's an upper bound it's in the second or third position. */
-    if (TYPE(ch) == COLON) {
-        if (NCH(n) > 1) {
-            node *n2 = CHILD(n, 1);
-
-            if (TYPE(n2) == test) {
-                upper = ast_for_expr(c, n2);
-                if (!upper)
-                    return NULL;
-            }
-        }
-    } else if (NCH(n) > 2) {
-        node *n2 = CHILD(n, 2);
-
-        if (TYPE(n2) == test) {
-            upper = ast_for_expr(c, n2);
-            if (!upper)
-                return NULL;
-        }
-    }
-
-    ch = CHILD(n, NCH(n) - 1);
-    if (TYPE(ch) == sliceop) {
-        if (NCH(ch) != 1) {
-            ch = CHILD(ch, 1);
-            if (TYPE(ch) == test) {
-                step = ast_for_expr(c, ch);
-                if (!step)
-                    return NULL;
-            }
-        }
-    }
-
-    return Slice(lower, upper, step, LINENO(n), n->n_col_offset,
-                 n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_binop(struct compiling *c, const node *n)
-{
-    /* Must account for a sequence of expressions.
-       How should A op B op C by represented?
-       BinOp(BinOp(A, op, B), op, C).
-    */
-
-    int i, nops;
-    expr_ty expr1, expr2, result;
-    operator_ty newoperator;
-
-    expr1 = ast_for_expr(c, CHILD(n, 0));
-    if (!expr1)
-        return NULL;
-
-    expr2 = ast_for_expr(c, CHILD(n, 2));
-    if (!expr2)
-        return NULL;
-
-    newoperator = get_operator(c, CHILD(n, 1));
-    if (!newoperator)
-        return NULL;
-
-    result = BinOp(expr1, newoperator, expr2, LINENO(n), n->n_col_offset,
-                   CHILD(n, 2)->n_end_lineno, CHILD(n, 2)->n_end_col_offset,
-                   c->c_arena);
-    if (!result)
-        return NULL;
-
-    nops = (NCH(n) - 1) / 2;
-    for (i = 1; i < nops; i++) {
-        expr_ty tmp_result, tmp;
-        const node* next_oper = CHILD(n, i * 2 + 1);
-
-        newoperator = get_operator(c, next_oper);
-        if (!newoperator)
-            return NULL;
-
-        tmp = ast_for_expr(c, CHILD(n, i * 2 + 2));
-        if (!tmp)
-            return NULL;
-
-        tmp_result = BinOp(result, newoperator, tmp,
-                           LINENO(n), n->n_col_offset,
-                           CHILD(n, i * 2 + 2)->n_end_lineno,
-                           CHILD(n, i * 2 + 2)->n_end_col_offset,
-                           c->c_arena);
-        if (!tmp_result)
-            return NULL;
-        result = tmp_result;
-    }
-    return result;
-}
-
-static expr_ty
-ast_for_trailer(struct compiling *c, const node *n, expr_ty left_expr, const node *start)
-{
-    /* trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
-       subscriptlist: subscript (',' subscript)* [',']
-       subscript: '.' '.' '.' | test | [test] ':' [test] [sliceop]
-     */
-    const node *n_copy = n;
-    REQ(n, trailer);
-    if (TYPE(CHILD(n, 0)) == LPAR) {
-        if (NCH(n) == 2)
-            return Call(left_expr, NULL, NULL, LINENO(start), start->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        else
-            return ast_for_call(c, CHILD(n, 1), left_expr,
-                                start, CHILD(n, 0), CHILD(n, 2));
-    }
-    else if (TYPE(CHILD(n, 0)) == DOT) {
-        PyObject *attr_id = NEW_IDENTIFIER(CHILD(n, 1));
-        if (!attr_id)
-            return NULL;
-        return Attribute(left_expr, attr_id, Load,
-                         LINENO(start), start->n_col_offset,
-                         n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else {
-        REQ(CHILD(n, 0), LSQB);
-        REQ(CHILD(n, 2), RSQB);
-        n = CHILD(n, 1);
-        if (NCH(n) == 1) {
-            expr_ty slc = ast_for_slice(c, CHILD(n, 0));
-            if (!slc)
-                return NULL;
-            return Subscript(left_expr, slc, Load, LINENO(start), start->n_col_offset,
-                             n_copy->n_end_lineno, n_copy->n_end_col_offset,
-                             c->c_arena);
-        }
-        else {
-            int j;
-            expr_ty slc, e;
-            asdl_seq *elts;
-            elts = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
-            if (!elts)
-                return NULL;
-            for (j = 0; j < NCH(n); j += 2) {
-                slc = ast_for_slice(c, CHILD(n, j));
-                if (!slc)
-                    return NULL;
-                asdl_seq_SET(elts, j / 2, slc);
-            }
-            e = Tuple(elts, Load, LINENO(n), n->n_col_offset,
-                      n->n_end_lineno, n->n_end_col_offset,
-                      c->c_arena);
-            if (!e)
-                return NULL;
-            return Subscript(left_expr, e,
-                             Load, LINENO(start), start->n_col_offset,
-                             n_copy->n_end_lineno, n_copy->n_end_col_offset,
-                             c->c_arena);
-        }
-    }
-}
-
-static expr_ty
-ast_for_factor(struct compiling *c, const node *n)
-{
-    expr_ty expression;
-
-    expression = ast_for_expr(c, CHILD(n, 1));
-    if (!expression)
-        return NULL;
-
-    switch (TYPE(CHILD(n, 0))) {
-        case PLUS:
-            return UnaryOp(UAdd, expression, LINENO(n), n->n_col_offset,
-                           n->n_end_lineno, n->n_end_col_offset,
-                           c->c_arena);
-        case MINUS:
-            return UnaryOp(USub, expression, LINENO(n), n->n_col_offset,
-                           n->n_end_lineno, n->n_end_col_offset,
-                           c->c_arena);
-        case TILDE:
-            return UnaryOp(Invert, expression, LINENO(n), n->n_col_offset,
-                           n->n_end_lineno, n->n_end_col_offset,
-                           c->c_arena);
-    }
-    PyErr_Format(PyExc_SystemError, "unhandled factor: %d",
-                 TYPE(CHILD(n, 0)));
-    return NULL;
-}
-
-static expr_ty
-ast_for_atom_expr(struct compiling *c, const node *n)
-{
-    int i, nch, start = 0;
-    expr_ty e;
-
-    REQ(n, atom_expr);
-    nch = NCH(n);
-
-    if (TYPE(CHILD(n, 0)) == AWAIT) {
-        if (c->c_feature_version < 5) {
-            ast_error(c, n,
-                      "Await expressions are only supported in Python 3.5 and greater");
-            return NULL;
-        }
-        start = 1;
-        assert(nch > 1);
-    }
-
-    e = ast_for_atom(c, CHILD(n, start));
-    if (!e)
-        return NULL;
-    if (nch == 1)
-        return e;
-    if (start && nch == 2) {
-        return Await(e, LINENO(n), n->n_col_offset,
-                     n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-
-    for (i = start + 1; i < nch; i++) {
-        node *ch = CHILD(n, i);
-        if (TYPE(ch) != trailer)
-            break;
-        e = ast_for_trailer(c, ch, e, CHILD(n, start));
-        if (!e)
-            return NULL;
-    }
-
-    if (start) {
-        /* there was an 'await' */
-        return Await(e, LINENO(n), n->n_col_offset,
-                     n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else {
-        return e;
-    }
-}
-
-static expr_ty
-ast_for_power(struct compiling *c, const node *n)
-{
-    /* power: atom trailer* ('**' factor)*
-     */
-    expr_ty e;
-    REQ(n, power);
-    e = ast_for_atom_expr(c, CHILD(n, 0));
-    if (!e)
-        return NULL;
-    if (NCH(n) == 1)
-        return e;
-    if (TYPE(CHILD(n, NCH(n) - 1)) == factor) {
-        expr_ty f = ast_for_expr(c, CHILD(n, NCH(n) - 1));
-        if (!f)
-            return NULL;
-        e = BinOp(e, Pow, f, LINENO(n), n->n_col_offset,
-                  n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    return e;
-}
-
-static expr_ty
-ast_for_starred(struct compiling *c, const node *n)
-{
-    expr_ty tmp;
-    REQ(n, star_expr);
-
-    tmp = ast_for_expr(c, CHILD(n, 1));
-    if (!tmp)
-        return NULL;
-
-    /* The Load context is changed later. */
-    return Starred(tmp, Load, LINENO(n), n->n_col_offset,
-                   n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-
-/* Do not name a variable 'expr'!  Will cause a compile error.
-*/
-
-static expr_ty
-ast_for_expr(struct compiling *c, const node *n)
-{
-    /* handle the full range of simple expressions
-       namedexpr_test: test [':=' test]
-       test: or_test ['if' or_test 'else' test] | lambdef
-       test_nocond: or_test | lambdef_nocond
-       or_test: and_test ('or' and_test)*
-       and_test: not_test ('and' not_test)*
-       not_test: 'not' not_test | comparison
-       comparison: expr (comp_op expr)*
-       expr: xor_expr ('|' xor_expr)*
-       xor_expr: and_expr ('^' and_expr)*
-       and_expr: shift_expr ('&' shift_expr)*
-       shift_expr: arith_expr (('<<'|'>>') arith_expr)*
-       arith_expr: term (('+'|'-') term)*
-       term: factor (('*'|'@'|'/'|'%'|'//') factor)*
-       factor: ('+'|'-'|'~') factor | power
-       power: atom_expr ['**' factor]
-       atom_expr: [AWAIT] atom trailer*
-       yield_expr: 'yield' [yield_arg]
-    */
-
-    asdl_seq *seq;
-    int i;
-
- loop:
-    switch (TYPE(n)) {
-        case namedexpr_test:
-            if (NCH(n) == 3)
-                return ast_for_namedexpr(c, n);
-            /* Fallthrough */
-        case test:
-        case test_nocond:
-            if (TYPE(CHILD(n, 0)) == lambdef ||
-                TYPE(CHILD(n, 0)) == lambdef_nocond)
-                return ast_for_lambdef(c, CHILD(n, 0));
-            else if (NCH(n) > 1)
-                return ast_for_ifexpr(c, n);
-            /* Fallthrough */
-        case or_test:
-        case and_test:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            seq = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
-            if (!seq)
-                return NULL;
-            for (i = 0; i < NCH(n); i += 2) {
-                expr_ty e = ast_for_expr(c, CHILD(n, i));
-                if (!e)
-                    return NULL;
-                asdl_seq_SET(seq, i / 2, e);
-            }
-            if (!strcmp(STR(CHILD(n, 1)), "and"))
-                return BoolOp(And, seq, LINENO(n), n->n_col_offset,
-                              n->n_end_lineno, n->n_end_col_offset,
-                              c->c_arena);
-            assert(!strcmp(STR(CHILD(n, 1)), "or"));
-            return BoolOp(Or, seq, LINENO(n), n->n_col_offset,
-                          n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        case not_test:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            else {
-                expr_ty expression = ast_for_expr(c, CHILD(n, 1));
-                if (!expression)
-                    return NULL;
-
-                return UnaryOp(Not, expression, LINENO(n), n->n_col_offset,
-                               n->n_end_lineno, n->n_end_col_offset,
-                               c->c_arena);
-            }
-        case comparison:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            else {
-                expr_ty expression;
-                asdl_int_seq *ops;
-                asdl_seq *cmps;
-                ops = _Py_asdl_int_seq_new(NCH(n) / 2, c->c_arena);
-                if (!ops)
-                    return NULL;
-                cmps = _Py_asdl_seq_new(NCH(n) / 2, c->c_arena);
-                if (!cmps) {
-                    return NULL;
-                }
-                for (i = 1; i < NCH(n); i += 2) {
-                    cmpop_ty newoperator;
-
-                    newoperator = ast_for_comp_op(c, CHILD(n, i));
-                    if (!newoperator) {
-                        return NULL;
-                    }
-
-                    expression = ast_for_expr(c, CHILD(n, i + 1));
-                    if (!expression) {
-                        return NULL;
-                    }
-
-                    asdl_seq_SET(ops, i / 2, newoperator);
-                    asdl_seq_SET(cmps, i / 2, expression);
-                }
-                expression = ast_for_expr(c, CHILD(n, 0));
-                if (!expression) {
-                    return NULL;
-                }
-
-                return Compare(expression, ops, cmps, LINENO(n), n->n_col_offset,
-                               n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            }
-
-        case star_expr:
-            return ast_for_starred(c, n);
-        /* The next five cases all handle BinOps.  The main body of code
-           is the same in each case, but the switch turned inside out to
-           reuse the code for each type of operator.
-         */
-        case expr:
-        case xor_expr:
-        case and_expr:
-        case shift_expr:
-        case arith_expr:
-        case term:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            return ast_for_binop(c, n);
-        case yield_expr: {
-            node *an = NULL;
-            node *en = NULL;
-            int is_from = 0;
-            expr_ty exp = NULL;
-            if (NCH(n) > 1)
-                an = CHILD(n, 1); /* yield_arg */
-            if (an) {
-                en = CHILD(an, NCH(an) - 1);
-                if (NCH(an) == 2) {
-                    is_from = 1;
-                    exp = ast_for_expr(c, en);
-                }
-                else
-                    exp = ast_for_testlist(c, en);
-                if (!exp)
-                    return NULL;
-            }
-            if (is_from)
-                return YieldFrom(exp, LINENO(n), n->n_col_offset,
-                                 n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            return Yield(exp, LINENO(n), n->n_col_offset,
-                         n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        case factor:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            return ast_for_factor(c, n);
-        case power:
-            return ast_for_power(c, n);
-        default:
-            PyErr_Format(PyExc_SystemError, "unhandled expr: %d", TYPE(n));
-            return NULL;
-    }
-    /* should never get here unless if error is set */
-    return NULL;
-}
-
-static expr_ty
-ast_for_call(struct compiling *c, const node *n, expr_ty func,
-             const node *start, const node *maybegenbeg, const node *closepar)
-{
-    /*
-      arglist: argument (',' argument)*  [',']
-      argument: ( test [comp_for] | '*' test | test '=' test | '**' test )
-    */
-
-    int i, nargs, nkeywords;
-    int ndoublestars;
-    asdl_seq *args;
-    asdl_seq *keywords;
-
-    REQ(n, arglist);
-
-    nargs = 0;
-    nkeywords = 0;
-    for (i = 0; i < NCH(n); i++) {
-        node *ch = CHILD(n, i);
-        if (TYPE(ch) == argument) {
-            if (NCH(ch) == 1)
-                nargs++;
-            else if (TYPE(CHILD(ch, 1)) == comp_for) {
-                nargs++;
-                if (!maybegenbeg) {
-                    ast_error(c, ch, "invalid syntax");
-                    return NULL;
-                }
-                if (NCH(n) > 1) {
-                    ast_error(c, ch, "Generator expression must be parenthesized");
-                    return NULL;
-                }
-            }
-            else if (TYPE(CHILD(ch, 0)) == STAR)
-                nargs++;
-            else if (TYPE(CHILD(ch, 1)) == COLONEQUAL) {
-                nargs++;
-            }
-            else
-                /* TYPE(CHILD(ch, 0)) == DOUBLESTAR or keyword argument */
-                nkeywords++;
-        }
-    }
-
-    args = _Py_asdl_seq_new(nargs, c->c_arena);
-    if (!args)
-        return NULL;
-    keywords = _Py_asdl_seq_new(nkeywords, c->c_arena);
-    if (!keywords)
-        return NULL;
-
-    nargs = 0;  /* positional arguments + iterable argument unpackings */
-    nkeywords = 0;  /* keyword arguments + keyword argument unpackings */
-    ndoublestars = 0;  /* just keyword argument unpackings */
-    for (i = 0; i < NCH(n); i++) {
-        node *ch = CHILD(n, i);
-        if (TYPE(ch) == argument) {
-            expr_ty e;
-            node *chch = CHILD(ch, 0);
-            if (NCH(ch) == 1) {
-                /* a positional argument */
-                if (nkeywords) {
-                    if (ndoublestars) {
-                        ast_error(c, chch,
-                                  "positional argument follows "
-                                  "keyword argument unpacking");
-                    }
-                    else {
-                        ast_error(c, chch,
-                                  "positional argument follows "
-                                  "keyword argument");
-                    }
-                    return NULL;
-                }
-                e = ast_for_expr(c, chch);
-                if (!e)
-                    return NULL;
-                asdl_seq_SET(args, nargs++, e);
-            }
-            else if (TYPE(chch) == STAR) {
-                /* an iterable argument unpacking */
-                expr_ty starred;
-                if (ndoublestars) {
-                    ast_error(c, chch,
-                              "iterable argument unpacking follows "
-                              "keyword argument unpacking");
-                    return NULL;
-                }
-                e = ast_for_expr(c, CHILD(ch, 1));
-                if (!e)
-                    return NULL;
-                starred = Starred(e, Load, LINENO(chch),
-                        chch->n_col_offset,
-                        e->end_lineno, e->end_col_offset,
-                        c->c_arena);
-                if (!starred)
-                    return NULL;
-                asdl_seq_SET(args, nargs++, starred);
-
-            }
-            else if (TYPE(chch) == DOUBLESTAR) {
-                /* a keyword argument unpacking */
-                keyword_ty kw;
-                i++;
-                e = ast_for_expr(c, CHILD(ch, 1));
-                if (!e)
-                    return NULL;
-                kw = keyword(NULL, e, chch->n_lineno, chch->n_col_offset,
-                             e->end_lineno, e->end_col_offset, c->c_arena);
-                asdl_seq_SET(keywords, nkeywords++, kw);
-                ndoublestars++;
-            }
-            else if (TYPE(CHILD(ch, 1)) == comp_for) {
-                /* the lone generator expression */
-                e = copy_location(ast_for_genexp(c, ch), maybegenbeg, closepar);
-                if (!e)
-                    return NULL;
-                asdl_seq_SET(args, nargs++, e);
-            }
-            else if (TYPE(CHILD(ch, 1)) == COLONEQUAL) {
-                /* treat colon equal as positional argument */
-                if (nkeywords) {
-                    if (ndoublestars) {
-                        ast_error(c, chch,
-                                  "positional argument follows "
-                                  "keyword argument unpacking");
-                    }
-                    else {
-                        ast_error(c, chch,
-                                  "positional argument follows "
-                                  "keyword argument");
-                    }
-                    return NULL;
-                }
-                e = ast_for_namedexpr(c, ch);
-                if (!e)
-                    return NULL;
-                asdl_seq_SET(args, nargs++, e);
-            }
-            else {
-                /* a keyword argument */
-                keyword_ty kw;
-                identifier key;
-
-                // To remain LL(1), the grammar accepts any test (basically, any
-                // expression) in the keyword slot of a call site.  So, we need
-                // to manually enforce that the keyword is a NAME here.
-                static const int name_tree[] = {
-                    test,
-                    or_test,
-                    and_test,
-                    not_test,
-                    comparison,
-                    expr,
-                    xor_expr,
-                    and_expr,
-                    shift_expr,
-                    arith_expr,
-                    term,
-                    factor,
-                    power,
-                    atom_expr,
-                    atom,
-                    0,
-                };
-                node *expr_node = chch;
-                for (int i = 0; name_tree[i]; i++) {
-                    if (TYPE(expr_node) != name_tree[i])
-                        break;
-                    if (NCH(expr_node) != 1)
-                        break;
-                    expr_node = CHILD(expr_node, 0);
-                }
-                if (TYPE(expr_node) != NAME) {
-                    ast_error(c, chch,
-                              "expression cannot contain assignment, "
-                              "perhaps you meant \"==\"?");
-                    return NULL;
-                }
-                key = new_identifier(STR(expr_node), c);
-                if (key == NULL) {
-                    return NULL;
-                }
-                if (forbidden_name(c, key, chch, 1)) {
-                    return NULL;
-                }
-                e = ast_for_expr(c, CHILD(ch, 2));
-                if (!e)
-                    return NULL;
-                kw = keyword(key, e, chch->n_lineno, chch->n_col_offset,
-                             e->end_lineno, e->end_col_offset, c->c_arena);
-
-                if (!kw)
-                    return NULL;
-                asdl_seq_SET(keywords, nkeywords++, kw);
-            }
-        }
-    }
-
-    return Call(func, args, keywords, LINENO(start), start->n_col_offset,
-                closepar->n_end_lineno, closepar->n_end_col_offset, c->c_arena);
-}
-
-static expr_ty
-ast_for_testlist(struct compiling *c, const node* n)
-{
-    /* testlist_comp: test (comp_for | (',' test)* [',']) */
-    /* testlist: test (',' test)* [','] */
-    assert(NCH(n) > 0);
-    if (TYPE(n) == testlist_comp) {
-        if (NCH(n) > 1)
-            assert(TYPE(CHILD(n, 1)) != comp_for);
-    }
-    else {
-        assert(TYPE(n) == testlist ||
-               TYPE(n) == testlist_star_expr);
-    }
-    if (NCH(n) == 1)
-        return ast_for_expr(c, CHILD(n, 0));
-    else {
-        asdl_seq *tmp = seq_for_testlist(c, n);
-        if (!tmp)
-            return NULL;
-        return Tuple(tmp, Load, LINENO(n), n->n_col_offset,
-                     n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-}
-
-static stmt_ty
-ast_for_expr_stmt(struct compiling *c, const node *n)
-{
-    REQ(n, expr_stmt);
-    /* expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
-                     [('=' (yield_expr|testlist_star_expr))+ [TYPE_COMMENT]] )
-       annassign: ':' test ['=' (yield_expr|testlist)]
-       testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
-       augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |
-                   '<<=' | '>>=' | '**=' | '//=')
-       test: ... here starts the operator precedence dance
-     */
-    int num = NCH(n);
-
-    if (num == 1) {
-        expr_ty e = ast_for_testlist(c, CHILD(n, 0));
-        if (!e)
-            return NULL;
-
-        return Expr(e, LINENO(n), n->n_col_offset,
-                    n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else if (TYPE(CHILD(n, 1)) == augassign) {
-        expr_ty expr1, expr2;
-        operator_ty newoperator;
-        node *ch = CHILD(n, 0);
-
-        expr1 = ast_for_testlist(c, ch);
-        if (!expr1)
-            return NULL;
-        /* Augmented assignments can only have a name, a subscript, or an
-          attribute on the left, though, so we have to explicitly check for
-          those. */
-        switch (expr1->kind) {
-            case Name_kind:
-            case Attribute_kind:
-            case Subscript_kind:
-                break;
-            default:
-                ast_error(c, ch, "'%s' is an illegal expression for augmented assignment",
-                          get_expr_name(expr1));
-                return NULL;
-        }
-
-        /* set_context checks that most expressions are not the left side. */
-        if(!set_context(c, expr1, Store, ch)) {
-            return NULL;
-        }
-
-        ch = CHILD(n, 2);
-        if (TYPE(ch) == testlist)
-            expr2 = ast_for_testlist(c, ch);
-        else
-            expr2 = ast_for_expr(c, ch);
-        if (!expr2)
-            return NULL;
-
-        newoperator = ast_for_augassign(c, CHILD(n, 1));
-        if (!newoperator)
-            return NULL;
-
-        return AugAssign(expr1, newoperator, expr2, LINENO(n), n->n_col_offset,
-                         n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else if (TYPE(CHILD(n, 1)) == annassign) {
-        expr_ty expr1, expr2, expr3;
-        node *ch = CHILD(n, 0);
-        node *deep, *ann = CHILD(n, 1);
-        int simple = 1;
-
-        /* AnnAssigns are only allowed in Python 3.6 or greater */
-        if (c->c_feature_version < 6) {
-            ast_error(c, ch,
-                      "Variable annotation syntax is only supported in Python 3.6 and greater");
-            return NULL;
-        }
-
-        /* we keep track of parens to qualify (x) as expression not name */
-        deep = ch;
-        while (NCH(deep) == 1) {
-            deep = CHILD(deep, 0);
-        }
-        if (NCH(deep) > 0 && TYPE(CHILD(deep, 0)) == LPAR) {
-            simple = 0;
-        }
-        expr1 = ast_for_testlist(c, ch);
-        if (!expr1) {
-            return NULL;
-        }
-        switch (expr1->kind) {
-            case Name_kind:
-                if (forbidden_name(c, expr1->v.Name.id, n, 0)) {
-                    return NULL;
-                }
-                expr1->v.Name.ctx = Store;
-                break;
-            case Attribute_kind:
-                if (forbidden_name(c, expr1->v.Attribute.attr, n, 1)) {
-                    return NULL;
-                }
-                expr1->v.Attribute.ctx = Store;
-                break;
-            case Subscript_kind:
-                expr1->v.Subscript.ctx = Store;
-                break;
-            case List_kind:
-                ast_error(c, ch,
-                          "only single target (not list) can be annotated");
-                return NULL;
-            case Tuple_kind:
-                ast_error(c, ch,
-                          "only single target (not tuple) can be annotated");
-                return NULL;
-            default:
-                ast_error(c, ch,
-                          "illegal target for annotation");
-                return NULL;
-        }
-
-        if (expr1->kind != Name_kind) {
-            simple = 0;
-        }
-        ch = CHILD(ann, 1);
-        expr2 = ast_for_expr(c, ch);
-        if (!expr2) {
-            return NULL;
-        }
-        if (NCH(ann) == 2) {
-            return AnnAssign(expr1, expr2, NULL, simple,
-                             LINENO(n), n->n_col_offset,
-                             n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        else {
-            ch = CHILD(ann, 3);
-            if (TYPE(ch) == testlist_star_expr) {
-                expr3 = ast_for_testlist(c, ch);
-            }
-            else {
-                expr3 = ast_for_expr(c, ch);
-            }
-            if (!expr3) {
-                return NULL;
-            }
-            return AnnAssign(expr1, expr2, expr3, simple,
-                             LINENO(n), n->n_col_offset,
-                             n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-    }
-    else {
-        int i, nch_minus_type, has_type_comment;
-        asdl_seq *targets;
-        node *value;
-        expr_ty expression;
-        string type_comment;
-
-        /* a normal assignment */
-        REQ(CHILD(n, 1), EQUAL);
-
-        has_type_comment = TYPE(CHILD(n, num - 1)) == TYPE_COMMENT;
-        nch_minus_type = num - has_type_comment;
-
-        targets = _Py_asdl_seq_new(nch_minus_type / 2, c->c_arena);
-        if (!targets)
-            return NULL;
-        for (i = 0; i < nch_minus_type - 2; i += 2) {
-            expr_ty e;
-            node *ch = CHILD(n, i);
-            if (TYPE(ch) == yield_expr) {
-                ast_error(c, ch, "assignment to yield expression not possible");
-                return NULL;
-            }
-            e = ast_for_testlist(c, ch);
-            if (!e)
-              return NULL;
-
-            /* set context to assign */
-            if (!set_context(c, e, Store, CHILD(n, i)))
-              return NULL;
-
-            asdl_seq_SET(targets, i / 2, e);
-        }
-        value = CHILD(n, nch_minus_type - 1);
-        if (TYPE(value) == testlist_star_expr)
-            expression = ast_for_testlist(c, value);
-        else
-            expression = ast_for_expr(c, value);
-        if (!expression)
-            return NULL;
-        if (has_type_comment) {
-            type_comment = NEW_TYPE_COMMENT(CHILD(n, nch_minus_type));
-            if (!type_comment)
-                return NULL;
-        }
-        else
-            type_comment = NULL;
-        return Assign(targets, expression, type_comment, LINENO(n), n->n_col_offset,
-                      n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-}
-
-
-static asdl_seq *
-ast_for_exprlist(struct compiling *c, const node *n, expr_context_ty context)
-{
-    asdl_seq *seq;
-    int i;
-    expr_ty e;
-
-    REQ(n, exprlist);
-
-    seq = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
-    if (!seq)
-        return NULL;
-    for (i = 0; i < NCH(n); i += 2) {
-        e = ast_for_expr(c, CHILD(n, i));
-        if (!e)
-            return NULL;
-        asdl_seq_SET(seq, i / 2, e);
-        if (context && !set_context(c, e, context, CHILD(n, i)))
-            return NULL;
-    }
-    return seq;
-}
-
-static stmt_ty
-ast_for_del_stmt(struct compiling *c, const node *n)
-{
-    asdl_seq *expr_list;
-
-    /* del_stmt: 'del' exprlist */
-    REQ(n, del_stmt);
-
-    expr_list = ast_for_exprlist(c, CHILD(n, 1), Del);
-    if (!expr_list)
-        return NULL;
-    return Delete(expr_list, LINENO(n), n->n_col_offset,
-                  n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_flow_stmt(struct compiling *c, const node *n)
-{
-    /*
-      flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt
-                 | yield_stmt
-      break_stmt: 'break'
-      continue_stmt: 'continue'
-      return_stmt: 'return' [testlist]
-      yield_stmt: yield_expr
-      yield_expr: 'yield' testlist | 'yield' 'from' test
-      raise_stmt: 'raise' [test [',' test [',' test]]]
-    */
-    node *ch;
-
-    REQ(n, flow_stmt);
-    ch = CHILD(n, 0);
-    switch (TYPE(ch)) {
-        case break_stmt:
-            return Break(LINENO(n), n->n_col_offset,
-                         n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        case continue_stmt:
-            return Continue(LINENO(n), n->n_col_offset,
-                            n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        case yield_stmt: { /* will reduce to yield_expr */
-            expr_ty exp = ast_for_expr(c, CHILD(ch, 0));
-            if (!exp)
-                return NULL;
-            return Expr(exp, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-        }
-        case return_stmt:
-            if (NCH(ch) == 1)
-                return Return(NULL, LINENO(n), n->n_col_offset,
-                              n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            else {
-                expr_ty expression = ast_for_testlist(c, CHILD(ch, 1));
-                if (!expression)
-                    return NULL;
-                return Return(expression, LINENO(n), n->n_col_offset,
-                              n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            }
-        case raise_stmt:
-            if (NCH(ch) == 1)
-                return Raise(NULL, NULL, LINENO(n), n->n_col_offset,
-                             n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            else if (NCH(ch) >= 2) {
-                expr_ty cause = NULL;
-                expr_ty expression = ast_for_expr(c, CHILD(ch, 1));
-                if (!expression)
-                    return NULL;
-                if (NCH(ch) == 4) {
-                    cause = ast_for_expr(c, CHILD(ch, 3));
-                    if (!cause)
-                        return NULL;
-                }
-                return Raise(expression, cause, LINENO(n), n->n_col_offset,
-                             n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            }
-            /* fall through */
-        default:
-            PyErr_Format(PyExc_SystemError,
-                         "unexpected flow_stmt: %d", TYPE(ch));
-            return NULL;
-    }
-}
-
-static alias_ty
-alias_for_import_name(struct compiling *c, const node *n, int store)
-{
-    /*
-      import_as_name: NAME ['as' NAME]
-      dotted_as_name: dotted_name ['as' NAME]
-      dotted_name: NAME ('.' NAME)*
-    */
-    identifier str, name;
-
- loop:
-    switch (TYPE(n)) {
-        case import_as_name: {
-            node *name_node = CHILD(n, 0);
-            str = NULL;
-            name = NEW_IDENTIFIER(name_node);
-            if (!name)
-                return NULL;
-            if (NCH(n) == 3) {
-                node *str_node = CHILD(n, 2);
-                str = NEW_IDENTIFIER(str_node);
-                if (!str)
-                    return NULL;
-                if (store && forbidden_name(c, str, str_node, 0))
-                    return NULL;
-            }
-            else {
-                if (forbidden_name(c, name, name_node, 0))
-                    return NULL;
-            }
-            return alias(name, str, c->c_arena);
-        }
-        case dotted_as_name:
-            if (NCH(n) == 1) {
-                n = CHILD(n, 0);
-                goto loop;
-            }
-            else {
-                node *asname_node = CHILD(n, 2);
-                alias_ty a = alias_for_import_name(c, CHILD(n, 0), 0);
-                if (!a)
-                    return NULL;
-                assert(!a->asname);
-                a->asname = NEW_IDENTIFIER(asname_node);
-                if (!a->asname)
-                    return NULL;
-                if (forbidden_name(c, a->asname, asname_node, 0))
-                    return NULL;
-                return a;
-            }
-        case dotted_name:
-            if (NCH(n) == 1) {
-                node *name_node = CHILD(n, 0);
-                name = NEW_IDENTIFIER(name_node);
-                if (!name)
-                    return NULL;
-                if (store && forbidden_name(c, name, name_node, 0))
-                    return NULL;
-                return alias(name, NULL, c->c_arena);
-            }
-            else {
-                /* Create a string of the form "a.b.c" */
-                int i;
-                size_t len;
-                char *s;
-                PyObject *uni;
-
-                len = 0;
-                for (i = 0; i < NCH(n); i += 2)
-                    /* length of string plus one for the dot */
-                    len += strlen(STR(CHILD(n, i))) + 1;
-                len--; /* the last name doesn't have a dot */
-                str = PyBytes_FromStringAndSize(NULL, len);
-                if (!str)
-                    return NULL;
-                s = PyBytes_AS_STRING(str);
-                if (!s)
-                    return NULL;
-                for (i = 0; i < NCH(n); i += 2) {
-                    char *sch = STR(CHILD(n, i));
-                    strcpy(s, STR(CHILD(n, i)));
-                    s += strlen(sch);
-                    *s++ = '.';
-                }
-                --s;
-                *s = '\0';
-                uni = PyUnicode_DecodeUTF8(PyBytes_AS_STRING(str),
-                                           PyBytes_GET_SIZE(str),
-                                           NULL);
-                Py_DECREF(str);
-                if (!uni)
-                    return NULL;
-                str = uni;
-                PyUnicode_InternInPlace(&str);
-                if (PyArena_AddPyObject(c->c_arena, str) < 0) {
-                    Py_DECREF(str);
-                    return NULL;
-                }
-                return alias(str, NULL, c->c_arena);
-            }
-        case STAR:
-            str = PyUnicode_InternFromString("*");
-            if (!str)
-                return NULL;
-            if (PyArena_AddPyObject(c->c_arena, str) < 0) {
-                Py_DECREF(str);
-                return NULL;
-            }
-            return alias(str, NULL, c->c_arena);
-        default:
-            PyErr_Format(PyExc_SystemError,
-                         "unexpected import name: %d", TYPE(n));
-            return NULL;
-    }
-}
-
-static stmt_ty
-ast_for_import_stmt(struct compiling *c, const node *n)
-{
-    /*
-      import_stmt: import_name | import_from
-      import_name: 'import' dotted_as_names
-      import_from: 'from' (('.' | '...')* dotted_name | ('.' | '...')+)
-                   'import' ('*' | '(' import_as_names ')' | import_as_names)
-    */
-    int lineno;
-    int col_offset;
-    int i;
-    asdl_seq *aliases;
-
-    REQ(n, import_stmt);
-    lineno = LINENO(n);
-    col_offset = n->n_col_offset;
-    n = CHILD(n, 0);
-    if (TYPE(n) == import_name) {
-        n = CHILD(n, 1);
-        REQ(n, dotted_as_names);
-        aliases = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
-        if (!aliases)
-                return NULL;
-        for (i = 0; i < NCH(n); i += 2) {
-            alias_ty import_alias = alias_for_import_name(c, CHILD(n, i), 1);
-            if (!import_alias)
-                return NULL;
-            asdl_seq_SET(aliases, i / 2, import_alias);
-        }
-        // Even though n is modified above, the end position is not changed
-        return Import(aliases, lineno, col_offset,
-                      n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else if (TYPE(n) == import_from) {
-        int n_children;
-        int idx, ndots = 0;
-        const node *n_copy = n;
-        alias_ty mod = NULL;
-        identifier modname = NULL;
-
-       /* Count the number of dots (for relative imports) and check for the
-          optional module name */
-        for (idx = 1; idx < NCH(n); idx++) {
-            if (TYPE(CHILD(n, idx)) == dotted_name) {
-                mod = alias_for_import_name(c, CHILD(n, idx), 0);
-                if (!mod)
-                    return NULL;
-                idx++;
-                break;
-            } else if (TYPE(CHILD(n, idx)) == ELLIPSIS) {
-                /* three consecutive dots are tokenized as one ELLIPSIS */
-                ndots += 3;
-                continue;
-            } else if (TYPE(CHILD(n, idx)) != DOT) {
-                break;
-            }
-            ndots++;
-        }
-        idx++; /* skip over the 'import' keyword */
-        switch (TYPE(CHILD(n, idx))) {
-        case STAR:
-            /* from ... import * */
-            n = CHILD(n, idx);
-            n_children = 1;
-            break;
-        case LPAR:
-            /* from ... import (x, y, z) */
-            n = CHILD(n, idx + 1);
-            n_children = NCH(n);
-            break;
-        case import_as_names:
-            /* from ... import x, y, z */
-            n = CHILD(n, idx);
-            n_children = NCH(n);
-            if (n_children % 2 == 0) {
-                ast_error(c, n,
-                          "trailing comma not allowed without"
-                          " surrounding parentheses");
-                return NULL;
-            }
-            break;
-        default:
-            ast_error(c, n, "Unexpected node-type in from-import");
-            return NULL;
-        }
-
-        aliases = _Py_asdl_seq_new((n_children + 1) / 2, c->c_arena);
-        if (!aliases)
-            return NULL;
-
-        /* handle "from ... import *" special b/c there's no children */
-        if (TYPE(n) == STAR) {
-            alias_ty import_alias = alias_for_import_name(c, n, 1);
-            if (!import_alias)
-                return NULL;
-            asdl_seq_SET(aliases, 0, import_alias);
-        }
-        else {
-            for (i = 0; i < NCH(n); i += 2) {
-                alias_ty import_alias = alias_for_import_name(c, CHILD(n, i), 1);
-                if (!import_alias)
-                    return NULL;
-                asdl_seq_SET(aliases, i / 2, import_alias);
-            }
-        }
-        if (mod != NULL)
-            modname = mod->name;
-        return ImportFrom(modname, aliases, ndots, lineno, col_offset,
-                          n_copy->n_end_lineno, n_copy->n_end_col_offset,
-                          c->c_arena);
-    }
-    PyErr_Format(PyExc_SystemError,
-                 "unknown import statement: starts with command '%s'",
-                 STR(CHILD(n, 0)));
-    return NULL;
-}
-
-static stmt_ty
-ast_for_global_stmt(struct compiling *c, const node *n)
-{
-    /* global_stmt: 'global' NAME (',' NAME)* */
-    identifier name;
-    asdl_seq *s;
-    int i;
-
-    REQ(n, global_stmt);
-    s = _Py_asdl_seq_new(NCH(n) / 2, c->c_arena);
-    if (!s)
-        return NULL;
-    for (i = 1; i < NCH(n); i += 2) {
-        name = NEW_IDENTIFIER(CHILD(n, i));
-        if (!name)
-            return NULL;
-        asdl_seq_SET(s, i / 2, name);
-    }
-    return Global(s, LINENO(n), n->n_col_offset,
-                  n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_nonlocal_stmt(struct compiling *c, const node *n)
-{
-    /* nonlocal_stmt: 'nonlocal' NAME (',' NAME)* */
-    identifier name;
-    asdl_seq *s;
-    int i;
-
-    REQ(n, nonlocal_stmt);
-    s = _Py_asdl_seq_new(NCH(n) / 2, c->c_arena);
-    if (!s)
-        return NULL;
-    for (i = 1; i < NCH(n); i += 2) {
-        name = NEW_IDENTIFIER(CHILD(n, i));
-        if (!name)
-            return NULL;
-        asdl_seq_SET(s, i / 2, name);
-    }
-    return Nonlocal(s, LINENO(n), n->n_col_offset,
-                    n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_assert_stmt(struct compiling *c, const node *n)
-{
-    /* assert_stmt: 'assert' test [',' test] */
-    REQ(n, assert_stmt);
-    if (NCH(n) == 2) {
-        expr_ty expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        return Assert(expression, NULL, LINENO(n), n->n_col_offset,
-                      n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    else if (NCH(n) == 4) {
-        expr_ty expr1, expr2;
-
-        expr1 = ast_for_expr(c, CHILD(n, 1));
-        if (!expr1)
-            return NULL;
-        expr2 = ast_for_expr(c, CHILD(n, 3));
-        if (!expr2)
-            return NULL;
-
-        return Assert(expr1, expr2, LINENO(n), n->n_col_offset,
-                      n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-    PyErr_Format(PyExc_SystemError,
-                 "improper number of parts to 'assert' statement: %d",
-                 NCH(n));
-    return NULL;
-}
-
-static asdl_seq *
-ast_for_suite(struct compiling *c, const node *n)
-{
-    /* suite: simple_stmt | NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT */
-    asdl_seq *seq;
-    stmt_ty s;
-    int i, total, num, end, pos = 0;
-    node *ch;
-
-    if (TYPE(n) != func_body_suite) {
-        REQ(n, suite);
-    }
-
-    total = num_stmts(n);
-    seq = _Py_asdl_seq_new(total, c->c_arena);
-    if (!seq)
-        return NULL;
-    if (TYPE(CHILD(n, 0)) == simple_stmt) {
-        n = CHILD(n, 0);
-        /* simple_stmt always ends with a NEWLINE,
-           and may have a trailing SEMI
-        */
-        end = NCH(n) - 1;
-        if (TYPE(CHILD(n, end - 1)) == SEMI)
-            end--;
-        /* loop by 2 to skip semi-colons */
-        for (i = 0; i < end; i += 2) {
-            ch = CHILD(n, i);
-            s = ast_for_stmt(c, ch);
-            if (!s)
-                return NULL;
-            asdl_seq_SET(seq, pos++, s);
-        }
-    }
-    else {
-        i = 2;
-        if (TYPE(CHILD(n, 1)) == TYPE_COMMENT) {
-            i += 2;
-            REQ(CHILD(n, 2), NEWLINE);
-        }
-
-        for (; i < (NCH(n) - 1); i++) {
-            ch = CHILD(n, i);
-            REQ(ch, stmt);
-            num = num_stmts(ch);
-            if (num == 1) {
-                /* small_stmt or compound_stmt with only one child */
-                s = ast_for_stmt(c, ch);
-                if (!s)
-                    return NULL;
-                asdl_seq_SET(seq, pos++, s);
-            }
-            else {
-                int j;
-                ch = CHILD(ch, 0);
-                REQ(ch, simple_stmt);
-                for (j = 0; j < NCH(ch); j += 2) {
-                    /* statement terminates with a semi-colon ';' */
-                    if (NCH(CHILD(ch, j)) == 0) {
-                        assert((j + 1) == NCH(ch));
-                        break;
-                    }
-                    s = ast_for_stmt(c, CHILD(ch, j));
-                    if (!s)
-                        return NULL;
-                    asdl_seq_SET(seq, pos++, s);
-                }
-            }
-        }
-    }
-    assert(pos == seq->size);
-    return seq;
-}
-
-static void
-get_last_end_pos(asdl_seq *s, int *end_lineno, int *end_col_offset)
-{
-    Py_ssize_t tot = asdl_seq_LEN(s);
-    // There must be no empty suites.
-    assert(tot > 0);
-    stmt_ty last = asdl_seq_GET(s, tot - 1);
-    *end_lineno = last->end_lineno;
-    *end_col_offset = last->end_col_offset;
-}
-
-static stmt_ty
-ast_for_if_stmt(struct compiling *c, const node *n)
-{
-    /* if_stmt: 'if' test ':' suite ('elif' test ':' suite)*
-       ['else' ':' suite]
-    */
-    char *s;
-    int end_lineno, end_col_offset;
-
-    REQ(n, if_stmt);
-
-    if (NCH(n) == 4) {
-        expr_ty expression;
-        asdl_seq *suite_seq;
-
-        expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        suite_seq = ast_for_suite(c, CHILD(n, 3));
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-
-        return If(expression, suite_seq, NULL, LINENO(n), n->n_col_offset,
-                  end_lineno, end_col_offset, c->c_arena);
-    }
-
-    s = STR(CHILD(n, 4));
-    /* s[2], the third character in the string, will be
-       's' for el_s_e, or
-       'i' for el_i_f
-    */
-    if (s[2] == 's') {
-        expr_ty expression;
-        asdl_seq *seq1, *seq2;
-
-        expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        seq1 = ast_for_suite(c, CHILD(n, 3));
-        if (!seq1)
-            return NULL;
-        seq2 = ast_for_suite(c, CHILD(n, 6));
-        if (!seq2)
-            return NULL;
-        get_last_end_pos(seq2, &end_lineno, &end_col_offset);
-
-        return If(expression, seq1, seq2, LINENO(n), n->n_col_offset,
-                  end_lineno, end_col_offset, c->c_arena);
-    }
-    else if (s[2] == 'i') {
-        int i, n_elif, has_else = 0;
-        expr_ty expression;
-        asdl_seq *suite_seq;
-        asdl_seq *orelse = NULL;
-        n_elif = NCH(n) - 4;
-        /* must reference the child n_elif+1 since 'else' token is third,
-           not fourth, child from the end. */
-        if (TYPE(CHILD(n, (n_elif + 1))) == NAME
-            && STR(CHILD(n, (n_elif + 1)))[2] == 's') {
-            has_else = 1;
-            n_elif -= 3;
-        }
-        n_elif /= 4;
-
-        if (has_else) {
-            asdl_seq *suite_seq2;
-
-            orelse = _Py_asdl_seq_new(1, c->c_arena);
-            if (!orelse)
-                return NULL;
-            expression = ast_for_expr(c, CHILD(n, NCH(n) - 6));
-            if (!expression)
-                return NULL;
-            suite_seq = ast_for_suite(c, CHILD(n, NCH(n) - 4));
-            if (!suite_seq)
-                return NULL;
-            suite_seq2 = ast_for_suite(c, CHILD(n, NCH(n) - 1));
-            if (!suite_seq2)
-                return NULL;
-            get_last_end_pos(suite_seq2, &end_lineno, &end_col_offset);
-
-            asdl_seq_SET(orelse, 0,
-                         If(expression, suite_seq, suite_seq2,
-                            LINENO(CHILD(n, NCH(n) - 7)),
-                            CHILD(n, NCH(n) - 7)->n_col_offset,
-                            end_lineno, end_col_offset, c->c_arena));
-            /* the just-created orelse handled the last elif */
-            n_elif--;
-        }
-
-        for (i = 0; i < n_elif; i++) {
-            int off = 5 + (n_elif - i - 1) * 4;
-            asdl_seq *newobj = _Py_asdl_seq_new(1, c->c_arena);
-            if (!newobj)
-                return NULL;
-            expression = ast_for_expr(c, CHILD(n, off));
-            if (!expression)
-                return NULL;
-            suite_seq = ast_for_suite(c, CHILD(n, off + 2));
-            if (!suite_seq)
-                return NULL;
-
-            if (orelse != NULL) {
-                get_last_end_pos(orelse, &end_lineno, &end_col_offset);
-            } else {
-                get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-            }
-            asdl_seq_SET(newobj, 0,
-                         If(expression, suite_seq, orelse,
-                            LINENO(CHILD(n, off - 1)),
-                            CHILD(n, off - 1)->n_col_offset,
-                            end_lineno, end_col_offset, c->c_arena));
-            orelse = newobj;
-        }
-        expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        suite_seq = ast_for_suite(c, CHILD(n, 3));
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(orelse, &end_lineno, &end_col_offset);
-        return If(expression, suite_seq, orelse,
-                  LINENO(n), n->n_col_offset,
-                  end_lineno, end_col_offset, c->c_arena);
-    }
-
-    PyErr_Format(PyExc_SystemError,
-                 "unexpected token in 'if' statement: %s", s);
-    return NULL;
-}
-
-static stmt_ty
-ast_for_while_stmt(struct compiling *c, const node *n)
-{
-    /* while_stmt: 'while' test ':' suite ['else' ':' suite] */
-    REQ(n, while_stmt);
-    int end_lineno, end_col_offset;
-
-    if (NCH(n) == 4) {
-        expr_ty expression;
-        asdl_seq *suite_seq;
-
-        expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        suite_seq = ast_for_suite(c, CHILD(n, 3));
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-        return While(expression, suite_seq, NULL, LINENO(n), n->n_col_offset,
-                     end_lineno, end_col_offset, c->c_arena);
-    }
-    else if (NCH(n) == 7) {
-        expr_ty expression;
-        asdl_seq *seq1, *seq2;
-
-        expression = ast_for_expr(c, CHILD(n, 1));
-        if (!expression)
-            return NULL;
-        seq1 = ast_for_suite(c, CHILD(n, 3));
-        if (!seq1)
-            return NULL;
-        seq2 = ast_for_suite(c, CHILD(n, 6));
-        if (!seq2)
-            return NULL;
-        get_last_end_pos(seq2, &end_lineno, &end_col_offset);
-
-        return While(expression, seq1, seq2, LINENO(n), n->n_col_offset,
-                     end_lineno, end_col_offset, c->c_arena);
-    }
-
-    PyErr_Format(PyExc_SystemError,
-                 "wrong number of tokens for 'while' statement: %d",
-                 NCH(n));
-    return NULL;
-}
-
-static stmt_ty
-ast_for_for_stmt(struct compiling *c, const node *n0, bool is_async)
-{
-    const node * const n = is_async ? CHILD(n0, 1) : n0;
-    asdl_seq *_target, *seq = NULL, *suite_seq;
-    expr_ty expression;
-    expr_ty target, first;
-    const node *node_target;
-    int end_lineno, end_col_offset;
-    int has_type_comment;
-    string type_comment;
-
-    if (is_async && c->c_feature_version < 5) {
-        ast_error(c, n,
-                  "Async for loops are only supported in Python 3.5 and greater");
-        return NULL;
-    }
-
-    /* for_stmt: 'for' exprlist 'in' testlist ':' [TYPE_COMMENT] suite ['else' ':' suite] */
-    REQ(n, for_stmt);
-
-    has_type_comment = TYPE(CHILD(n, 5)) == TYPE_COMMENT;
-
-    if (NCH(n) == 9 + has_type_comment) {
-        seq = ast_for_suite(c, CHILD(n, 8 + has_type_comment));
-        if (!seq)
-            return NULL;
-    }
-
-    node_target = CHILD(n, 1);
-    _target = ast_for_exprlist(c, node_target, Store);
-    if (!_target)
-        return NULL;
-    /* Check the # of children rather than the length of _target, since
-       for x, in ... has 1 element in _target, but still requires a Tuple. */
-    first = (expr_ty)asdl_seq_GET(_target, 0);
-    if (NCH(node_target) == 1)
-        target = first;
-    else
-        target = Tuple(_target, Store, first->lineno, first->col_offset,
-                       node_target->n_end_lineno, node_target->n_end_col_offset,
-                       c->c_arena);
-
-    expression = ast_for_testlist(c, CHILD(n, 3));
-    if (!expression)
-        return NULL;
-    suite_seq = ast_for_suite(c, CHILD(n, 5 + has_type_comment));
-    if (!suite_seq)
-        return NULL;
-
-    if (seq != NULL) {
-        get_last_end_pos(seq, &end_lineno, &end_col_offset);
-    } else {
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-    }
-
-    if (has_type_comment) {
-        type_comment = NEW_TYPE_COMMENT(CHILD(n, 5));
-        if (!type_comment)
-            return NULL;
-    }
-    else
-        type_comment = NULL;
-
-    if (is_async)
-        return AsyncFor(target, expression, suite_seq, seq, type_comment,
-                        LINENO(n0), n0->n_col_offset,
-                        end_lineno, end_col_offset, c->c_arena);
-    else
-        return For(target, expression, suite_seq, seq, type_comment,
-                   LINENO(n), n->n_col_offset,
-                   end_lineno, end_col_offset, c->c_arena);
-}
-
-static excepthandler_ty
-ast_for_except_clause(struct compiling *c, const node *exc, node *body)
-{
-    /* except_clause: 'except' [test ['as' test]] */
-    int end_lineno, end_col_offset;
-    REQ(exc, except_clause);
-    REQ(body, suite);
-
-    if (NCH(exc) == 1) {
-        asdl_seq *suite_seq = ast_for_suite(c, body);
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-
-        return ExceptHandler(NULL, NULL, suite_seq, LINENO(exc),
-                             exc->n_col_offset,
-                             end_lineno, end_col_offset, c->c_arena);
-    }
-    else if (NCH(exc) == 2) {
-        expr_ty expression;
-        asdl_seq *suite_seq;
-
-        expression = ast_for_expr(c, CHILD(exc, 1));
-        if (!expression)
-            return NULL;
-        suite_seq = ast_for_suite(c, body);
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-
-        return ExceptHandler(expression, NULL, suite_seq, LINENO(exc),
-                             exc->n_col_offset,
-                             end_lineno, end_col_offset, c->c_arena);
-    }
-    else if (NCH(exc) == 4) {
-        asdl_seq *suite_seq;
-        expr_ty expression;
-        identifier e = NEW_IDENTIFIER(CHILD(exc, 3));
-        if (!e)
-            return NULL;
-        if (forbidden_name(c, e, CHILD(exc, 3), 0))
-            return NULL;
-        expression = ast_for_expr(c, CHILD(exc, 1));
-        if (!expression)
-            return NULL;
-        suite_seq = ast_for_suite(c, body);
-        if (!suite_seq)
-            return NULL;
-        get_last_end_pos(suite_seq, &end_lineno, &end_col_offset);
-
-        return ExceptHandler(expression, e, suite_seq, LINENO(exc),
-                             exc->n_col_offset,
-                             end_lineno, end_col_offset, c->c_arena);
-    }
-
-    PyErr_Format(PyExc_SystemError,
-                 "wrong number of children for 'except' clause: %d",
-                 NCH(exc));
-    return NULL;
-}
-
-static stmt_ty
-ast_for_try_stmt(struct compiling *c, const node *n)
-{
-    const int nch = NCH(n);
-    int end_lineno, end_col_offset, n_except = (nch - 3)/3;
-    asdl_seq *body, *handlers = NULL, *orelse = NULL, *finally = NULL;
-    excepthandler_ty last_handler;
-
-    REQ(n, try_stmt);
-
-    body = ast_for_suite(c, CHILD(n, 2));
-    if (body == NULL)
-        return NULL;
-
-    if (TYPE(CHILD(n, nch - 3)) == NAME) {
-        if (strcmp(STR(CHILD(n, nch - 3)), "finally") == 0) {
-            if (nch >= 9 && TYPE(CHILD(n, nch - 6)) == NAME) {
-                /* we can assume it's an "else",
-                   because nch >= 9 for try-else-finally and
-                   it would otherwise have a type of except_clause */
-                orelse = ast_for_suite(c, CHILD(n, nch - 4));
-                if (orelse == NULL)
-                    return NULL;
-                n_except--;
-            }
-
-            finally = ast_for_suite(c, CHILD(n, nch - 1));
-            if (finally == NULL)
-                return NULL;
-            n_except--;
-        }
-        else {
-            /* we can assume it's an "else",
-               otherwise it would have a type of except_clause */
-            orelse = ast_for_suite(c, CHILD(n, nch - 1));
-            if (orelse == NULL)
-                return NULL;
-            n_except--;
-        }
-    }
-    else if (TYPE(CHILD(n, nch - 3)) != except_clause) {
-        ast_error(c, n, "malformed 'try' statement");
-        return NULL;
-    }
-
-    if (n_except > 0) {
-        int i;
-        /* process except statements to create a try ... except */
-        handlers = _Py_asdl_seq_new(n_except, c->c_arena);
-        if (handlers == NULL)
-            return NULL;
-
-        for (i = 0; i < n_except; i++) {
-            excepthandler_ty e = ast_for_except_clause(c, CHILD(n, 3 + i * 3),
-                                                       CHILD(n, 5 + i * 3));
-            if (!e)
-                return NULL;
-            asdl_seq_SET(handlers, i, e);
-        }
-    }
-
-    assert(finally != NULL || asdl_seq_LEN(handlers));
-        if (finally != NULL) {
-        // finally is always last
-        get_last_end_pos(finally, &end_lineno, &end_col_offset);
-    } else if (orelse != NULL) {
-        // otherwise else is last
-        get_last_end_pos(orelse, &end_lineno, &end_col_offset);
-    } else {
-        // inline the get_last_end_pos logic due to layout mismatch
-        last_handler = (excepthandler_ty) asdl_seq_GET(handlers, n_except - 1);
-        end_lineno = last_handler->end_lineno;
-        end_col_offset = last_handler->end_col_offset;
-    }
-    return Try(body, handlers, orelse, finally, LINENO(n), n->n_col_offset,
-               end_lineno, end_col_offset, c->c_arena);
-}
-
-/* with_item: test ['as' expr] */
-static withitem_ty
-ast_for_with_item(struct compiling *c, const node *n)
-{
-    expr_ty context_expr, optional_vars = NULL;
-
-    REQ(n, with_item);
-    context_expr = ast_for_expr(c, CHILD(n, 0));
-    if (!context_expr)
-        return NULL;
-    if (NCH(n) == 3) {
-        optional_vars = ast_for_expr(c, CHILD(n, 2));
-
-        if (!optional_vars) {
-            return NULL;
-        }
-        if (!set_context(c, optional_vars, Store, n)) {
-            return NULL;
-        }
-    }
-
-    return withitem(context_expr, optional_vars, c->c_arena);
-}
-
-/* with_stmt: 'with' with_item (',' with_item)*  ':' [TYPE_COMMENT] suite */
-static stmt_ty
-ast_for_with_stmt(struct compiling *c, const node *n0, bool is_async)
-{
-    const node * const n = is_async ? CHILD(n0, 1) : n0;
-    int i, n_items, nch_minus_type, has_type_comment, end_lineno, end_col_offset;
-    asdl_seq *items, *body;
-    string type_comment;
-
-    if (is_async && c->c_feature_version < 5) {
-        ast_error(c, n,
-                  "Async with statements are only supported in Python 3.5 and greater");
-        return NULL;
-    }
-
-    REQ(n, with_stmt);
-
-    has_type_comment = TYPE(CHILD(n, NCH(n) - 2)) == TYPE_COMMENT;
-    nch_minus_type = NCH(n) - has_type_comment;
-
-    n_items = (nch_minus_type - 2) / 2;
-    items = _Py_asdl_seq_new(n_items, c->c_arena);
-    if (!items)
-        return NULL;
-    for (i = 1; i < nch_minus_type - 2; i += 2) {
-        withitem_ty item = ast_for_with_item(c, CHILD(n, i));
-        if (!item)
-            return NULL;
-        asdl_seq_SET(items, (i - 1) / 2, item);
-    }
-
-    body = ast_for_suite(c, CHILD(n, NCH(n) - 1));
-    if (!body)
-        return NULL;
-    get_last_end_pos(body, &end_lineno, &end_col_offset);
-
-    if (has_type_comment) {
-        type_comment = NEW_TYPE_COMMENT(CHILD(n, NCH(n) - 2));
-        if (!type_comment)
-            return NULL;
-    }
-    else
-        type_comment = NULL;
-
-    if (is_async)
-        return AsyncWith(items, body, type_comment, LINENO(n0), n0->n_col_offset,
-                         end_lineno, end_col_offset, c->c_arena);
-    else
-        return With(items, body, type_comment, LINENO(n), n->n_col_offset,
-                    end_lineno, end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_classdef(struct compiling *c, const node *n, asdl_seq *decorator_seq)
-{
-    /* classdef: 'class' NAME ['(' arglist ')'] ':' suite */
-    PyObject *classname;
-    asdl_seq *s;
-    expr_ty call;
-    int end_lineno, end_col_offset;
-
-    REQ(n, classdef);
-
-    if (NCH(n) == 4) { /* class NAME ':' suite */
-        s = ast_for_suite(c, CHILD(n, 3));
-        if (!s)
-            return NULL;
-        get_last_end_pos(s, &end_lineno, &end_col_offset);
-
-        classname = NEW_IDENTIFIER(CHILD(n, 1));
-        if (!classname)
-            return NULL;
-        if (forbidden_name(c, classname, CHILD(n, 3), 0))
-            return NULL;
-        return ClassDef(classname, NULL, NULL, s, decorator_seq,
-                        LINENO(n), n->n_col_offset,
-                        end_lineno, end_col_offset, c->c_arena);
-    }
-
-    if (TYPE(CHILD(n, 3)) == RPAR) { /* class NAME '(' ')' ':' suite */
-        s = ast_for_suite(c, CHILD(n, 5));
-        if (!s)
-            return NULL;
-        get_last_end_pos(s, &end_lineno, &end_col_offset);
-
-        classname = NEW_IDENTIFIER(CHILD(n, 1));
-        if (!classname)
-            return NULL;
-        if (forbidden_name(c, classname, CHILD(n, 3), 0))
-            return NULL;
-        return ClassDef(classname, NULL, NULL, s, decorator_seq,
-                        LINENO(n), n->n_col_offset,
-                        end_lineno, end_col_offset, c->c_arena);
-    }
-
-    /* class NAME '(' arglist ')' ':' suite */
-    /* build up a fake Call node so we can extract its pieces */
-    {
-        PyObject *dummy_name;
-        expr_ty dummy;
-        dummy_name = NEW_IDENTIFIER(CHILD(n, 1));
-        if (!dummy_name)
-            return NULL;
-        dummy = Name(dummy_name, Load, LINENO(n), n->n_col_offset,
-                     CHILD(n, 1)->n_end_lineno, CHILD(n, 1)->n_end_col_offset,
-                     c->c_arena);
-        call = ast_for_call(c, CHILD(n, 3), dummy,
-                            CHILD(n, 1), NULL, CHILD(n, 4));
-        if (!call)
-            return NULL;
-    }
-    s = ast_for_suite(c, CHILD(n, 6));
-    if (!s)
-        return NULL;
-    get_last_end_pos(s, &end_lineno, &end_col_offset);
-
-    classname = NEW_IDENTIFIER(CHILD(n, 1));
-    if (!classname)
-        return NULL;
-    if (forbidden_name(c, classname, CHILD(n, 1), 0))
-        return NULL;
-
-    return ClassDef(classname, call->v.Call.args, call->v.Call.keywords, s,
-                    decorator_seq, LINENO(n), n->n_col_offset,
-                    end_lineno, end_col_offset, c->c_arena);
-}
-
-static stmt_ty
-ast_for_stmt(struct compiling *c, const node *n)
-{
-    if (TYPE(n) == stmt) {
-        assert(NCH(n) == 1);
-        n = CHILD(n, 0);
-    }
-    if (TYPE(n) == simple_stmt) {
-        assert(num_stmts(n) == 1);
-        n = CHILD(n, 0);
-    }
-    if (TYPE(n) == small_stmt) {
-        n = CHILD(n, 0);
-        /* small_stmt: expr_stmt | del_stmt | pass_stmt | flow_stmt
-                  | import_stmt | global_stmt | nonlocal_stmt | assert_stmt
-        */
-        switch (TYPE(n)) {
-            case expr_stmt:
-                return ast_for_expr_stmt(c, n);
-            case del_stmt:
-                return ast_for_del_stmt(c, n);
-            case pass_stmt:
-                return Pass(LINENO(n), n->n_col_offset,
-                            n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-            case flow_stmt:
-                return ast_for_flow_stmt(c, n);
-            case import_stmt:
-                return ast_for_import_stmt(c, n);
-            case global_stmt:
-                return ast_for_global_stmt(c, n);
-            case nonlocal_stmt:
-                return ast_for_nonlocal_stmt(c, n);
-            case assert_stmt:
-                return ast_for_assert_stmt(c, n);
-            default:
-                PyErr_Format(PyExc_SystemError,
-                             "unhandled small_stmt: TYPE=%d NCH=%d\n",
-                             TYPE(n), NCH(n));
-                return NULL;
-        }
-    }
-    else {
-        /* compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt
-                        | funcdef | classdef | decorated | async_stmt
-        */
-        node *ch = CHILD(n, 0);
-        REQ(n, compound_stmt);
-        switch (TYPE(ch)) {
-            case if_stmt:
-                return ast_for_if_stmt(c, ch);
-            case while_stmt:
-                return ast_for_while_stmt(c, ch);
-            case for_stmt:
-                return ast_for_for_stmt(c, ch, 0);
-            case try_stmt:
-                return ast_for_try_stmt(c, ch);
-            case with_stmt:
-                return ast_for_with_stmt(c, ch, 0);
-            case funcdef:
-                return ast_for_funcdef(c, ch, NULL);
-            case classdef:
-                return ast_for_classdef(c, ch, NULL);
-            case decorated:
-                return ast_for_decorated(c, ch);
-            case async_stmt:
-                return ast_for_async_stmt(c, ch);
-            default:
-                PyErr_Format(PyExc_SystemError,
-                             "unhandled compound_stmt: TYPE=%d NCH=%d\n",
-                             TYPE(n), NCH(n));
-                return NULL;
-        }
-    }
-}
-
-static PyObject *
-parsenumber_raw(struct compiling *c, const char *s)
-{
-    const char *end;
-    long x;
-    double dx;
-    Py_complex compl;
-    int imflag;
-
-    assert(s != NULL);
-    errno = 0;
-    end = s + strlen(s) - 1;
-    imflag = *end == 'j' || *end == 'J';
-    if (s[0] == '0') {
-        x = (long) PyOS_strtoul(s, (char **)&end, 0);
-        if (x < 0 && errno == 0) {
-            return PyLong_FromString(s, (char **)0, 0);
-        }
-    }
-    else
-        x = PyOS_strtol(s, (char **)&end, 0);
-    if (*end == '\0') {
-        if (errno != 0)
-            return PyLong_FromString(s, (char **)0, 0);
-        return PyLong_FromLong(x);
-    }
-    /* XXX Huge floats may silently fail */
-    if (imflag) {
-        compl.real = 0.;
-        compl.imag = PyOS_string_to_double(s, (char **)&end, NULL);
-        if (compl.imag == -1.0 && PyErr_Occurred())
-            return NULL;
-        return PyComplex_FromCComplex(compl);
-    }
-    else
-    {
-        dx = PyOS_string_to_double(s, NULL, NULL);
-        if (dx == -1.0 && PyErr_Occurred())
-            return NULL;
-        return PyFloat_FromDouble(dx);
-    }
-}
-
-static PyObject *
-parsenumber(struct compiling *c, const char *s)
-{
-    char *dup, *end;
-    PyObject *res = NULL;
-
-    assert(s != NULL);
-
-    if (strchr(s, '_') == NULL) {
-        return parsenumber_raw(c, s);
-    }
-    /* Create a duplicate without underscores. */
-    dup = PyMem_Malloc(strlen(s) + 1);
-    if (dup == NULL) {
-        return PyErr_NoMemory();
-    }
-    end = dup;
-    for (; *s; s++) {
-        if (*s != '_') {
-            *end++ = *s;
-        }
-    }
-    *end = '\0';
-    res = parsenumber_raw(c, dup);
-    PyMem_Free(dup);
-    return res;
-}
-
-static PyObject *
-decode_utf8(struct compiling *c, const char **sPtr, const char *end)
-{
-    const char *s, *t;
-    t = s = *sPtr;
-    /* while (s < end && *s != '\\') s++; */ /* inefficient for u".." */
-    while (s < end && (*s & 0x80)) s++;
-    *sPtr = s;
-    return PyUnicode_DecodeUTF8(t, s - t, NULL);
-}
-
-static int
-warn_invalid_escape_sequence(struct compiling *c, const node *n,
-                             unsigned char first_invalid_escape_char)
-{
-    PyObject *msg = PyUnicode_FromFormat("invalid escape sequence \\%c",
-                                         first_invalid_escape_char);
-    if (msg == NULL) {
-        return -1;
-    }
-    if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg,
-                                   c->c_filename, LINENO(n),
-                                   NULL, NULL) < 0)
-    {
-        if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) {
-            /* Replace the DeprecationWarning exception with a SyntaxError
-               to get a more accurate error report */
-            PyErr_Clear();
-            ast_error(c, n, "%U", msg);
-        }
-        Py_DECREF(msg);
-        return -1;
-    }
-    Py_DECREF(msg);
-    return 0;
-}
-
-static PyObject *
-decode_unicode_with_escapes(struct compiling *c, const node *n, const char *s,
-                            size_t len)
-{
-    PyObject *v, *u;
-    char *buf;
-    char *p;
-    const char *end;
-
-    /* check for integer overflow */
-    if (len > SIZE_MAX / 6)
-        return NULL;
-    /* "ä" (2 bytes) may become "\U000000E4" (10 bytes), or 1:5
-       "\ä" (3 bytes) may become "\u005c\U000000E4" (16 bytes), or ~1:6 */
-    u = PyBytes_FromStringAndSize((char *)NULL, len * 6);
-    if (u == NULL)
-        return NULL;
-    p = buf = PyBytes_AsString(u);
-    end = s + len;
-    while (s < end) {
-        if (*s == '\\') {
-            *p++ = *s++;
-            if (s >= end || *s & 0x80) {
-                strcpy(p, "u005c");
-                p += 5;
-                if (s >= end)
-                    break;
-            }
-        }
-        if (*s & 0x80) { /* XXX inefficient */
-            PyObject *w;
-            int kind;
-            const void *data;
-            Py_ssize_t len, i;
-            w = decode_utf8(c, &s, end);
-            if (w == NULL) {
-                Py_DECREF(u);
-                return NULL;
-            }
-            kind = PyUnicode_KIND(w);
-            data = PyUnicode_DATA(w);
-            len = PyUnicode_GET_LENGTH(w);
-            for (i = 0; i < len; i++) {
-                Py_UCS4 chr = PyUnicode_READ(kind, data, i);
-                sprintf(p, "\\U%08x", chr);
-                p += 10;
-            }
-            /* Should be impossible to overflow */
-            assert(p - buf <= PyBytes_GET_SIZE(u));
-            Py_DECREF(w);
-        } else {
-            *p++ = *s++;
-        }
-    }
-    len = p - buf;
-    s = buf;
-
-    const char *first_invalid_escape;
-    v = _PyUnicode_DecodeUnicodeEscape(s, len, NULL, &first_invalid_escape);
-
-    if (v != NULL && first_invalid_escape != NULL) {
-        if (warn_invalid_escape_sequence(c, n, *first_invalid_escape) < 0) {
-            /* We have not decref u before because first_invalid_escape points
-               inside u. */
-            Py_XDECREF(u);
-            Py_DECREF(v);
-            return NULL;
-        }
-    }
-    Py_XDECREF(u);
-    return v;
-}
-
-static PyObject *
-decode_bytes_with_escapes(struct compiling *c, const node *n, const char *s,
-                          size_t len)
-{
-    const char *first_invalid_escape;
-    PyObject *result = _PyBytes_DecodeEscape(s, len, NULL,
-                                             &first_invalid_escape);
-    if (result == NULL)
-        return NULL;
-
-    if (first_invalid_escape != NULL) {
-        if (warn_invalid_escape_sequence(c, n, *first_invalid_escape) < 0) {
-            Py_DECREF(result);
-            return NULL;
-        }
-    }
-    return result;
-}
-
-/* Shift locations for the given node and all its children by adding `lineno`
-   and `col_offset` to existing locations. */
-static void fstring_shift_node_locations(node *n, int lineno, int col_offset)
-{
-    n->n_col_offset = n->n_col_offset + col_offset;
-    n->n_end_col_offset = n->n_end_col_offset + col_offset;
-    for (int i = 0; i < NCH(n); ++i) {
-        if (n->n_lineno && n->n_lineno < CHILD(n, i)->n_lineno) {
-            /* Shifting column offsets unnecessary if there's been newlines. */
-            col_offset = 0;
-        }
-        fstring_shift_node_locations(CHILD(n, i), lineno, col_offset);
-    }
-    n->n_lineno = n->n_lineno + lineno;
-    n->n_end_lineno = n->n_end_lineno + lineno;
-}
-
-/* Fix locations for the given node and its children.
-
-   `parent` is the enclosing node.
-   `n` is the node which locations are going to be fixed relative to parent.
-   `expr_str` is the child node's string representation, including braces.
-*/
-static void
-fstring_fix_node_location(const node *parent, node *n, char *expr_str)
-{
-    char *substr = NULL;
-    char *start;
-    int lines = LINENO(parent) - 1;
-    int cols = parent->n_col_offset;
-    /* Find the full fstring to fix location information in `n`. */
-    while (parent && parent->n_type != STRING)
-        parent = parent->n_child;
-    if (parent && parent->n_str) {
-        substr = strstr(parent->n_str, expr_str);
-        if (substr) {
-            start = substr;
-            while (start > parent->n_str) {
-                if (start[0] == '\n')
-                    break;
-                start--;
-            }
-            cols += (int)(substr - start);
-            /* adjust the start based on the number of newlines encountered
-               before the f-string expression */
-            for (char* p = parent->n_str; p < substr; p++) {
-                if (*p == '\n') {
-                    lines++;
-                }
-            }
-        }
-    }
-    fstring_shift_node_locations(n, lines, cols);
-}
-
-/* Compile this expression in to an expr_ty.  Add parens around the
-   expression, in order to allow leading spaces in the expression. */
-static expr_ty
-fstring_compile_expr(const char *expr_start, const char *expr_end,
-                     struct compiling *c, const node *n)
-
-{
-    node *mod_n;
-    mod_ty mod;
-    char *str;
-    Py_ssize_t len;
-    const char *s;
-
-    assert(expr_end >= expr_start);
-    assert(*(expr_start-1) == '{');
-    assert(*expr_end == '}' || *expr_end == '!' || *expr_end == ':' ||
-           *expr_end == '=');
-
-    /* If the substring is all whitespace, it's an error.  We need to catch this
-       here, and not when we call PyParser_SimpleParseStringFlagsFilename,
-       because turning the expression '' in to '()' would go from being invalid
-       to valid. */
-    for (s = expr_start; s != expr_end; s++) {
-        char c = *s;
-        /* The Python parser ignores only the following whitespace
-           characters (\r already is converted to \n). */
-        if (!(c == ' ' || c == '\t' || c == '\n' || c == '\f')) {
-            break;
-        }
-    }
-    if (s == expr_end) {
-        ast_error(c, n, "f-string: empty expression not allowed");
-        return NULL;
-    }
-
-    len = expr_end - expr_start;
-    /* Allocate 3 extra bytes: open paren, close paren, null byte. */
-    str = PyMem_RawMalloc(len + 3);
-    if (str == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-
-    str[0] = '(';
-    memcpy(str+1, expr_start, len);
-    str[len+1] = ')';
-    str[len+2] = 0;
-
-    PyCompilerFlags cf = _PyCompilerFlags_INIT;
-    cf.cf_flags = PyCF_ONLY_AST;
-    mod_n = PyParser_SimpleParseStringFlagsFilename(str, "<fstring>",
-                                                    Py_eval_input, 0);
-    if (!mod_n) {
-        PyMem_RawFree(str);
-        return NULL;
-    }
-    /* Reuse str to find the correct column offset. */
-    str[0] = '{';
-    str[len+1] = '}';
-    fstring_fix_node_location(n, mod_n, str);
-    mod = PyAST_FromNode(mod_n, &cf, "<fstring>", c->c_arena);
-    PyMem_RawFree(str);
-    PyNode_Free(mod_n);
-    if (!mod)
-        return NULL;
-    return mod->v.Expression.body;
-}
-
-/* Return -1 on error.
-
-   Return 0 if we reached the end of the literal.
-
-   Return 1 if we haven't reached the end of the literal, but we want
-   the caller to process the literal up to this point. Used for
-   doubled braces.
-*/
-static int
-fstring_find_literal(const char **str, const char *end, int raw,
-                     PyObject **literal, int recurse_lvl,
-                     struct compiling *c, const node *n)
-{
-    /* Get any literal string. It ends when we hit an un-doubled left
-       brace (which isn't part of a unicode name escape such as
-       "\N{EULER CONSTANT}"), or the end of the string. */
-
-    const char *s = *str;
-    const char *literal_start = s;
-    int result = 0;
-
-    assert(*literal == NULL);
-    while (s < end) {
-        char ch = *s++;
-        if (!raw && ch == '\\' && s < end) {
-            ch = *s++;
-            if (ch == 'N') {
-                if (s < end && *s++ == '{') {
-                    while (s < end && *s++ != '}') {
-                    }
-                    continue;
-                }
-                break;
-            }
-            if (ch == '{' && warn_invalid_escape_sequence(c, n, ch) < 0) {
-                return -1;
-            }
-        }
-        if (ch == '{' || ch == '}') {
-            /* Check for doubled braces, but only at the top level. If
-               we checked at every level, then f'{0:{3}}' would fail
-               with the two closing braces. */
-            if (recurse_lvl == 0) {
-                if (s < end && *s == ch) {
-                    /* We're going to tell the caller that the literal ends
-                       here, but that they should continue scanning. But also
-                       skip over the second brace when we resume scanning. */
-                    *str = s + 1;
-                    result = 1;
-                    goto done;
-                }
-
-                /* Where a single '{' is the start of a new expression, a
-                   single '}' is not allowed. */
-                if (ch == '}') {
-                    *str = s - 1;
-                    ast_error(c, n, "f-string: single '}' is not allowed");
-                    return -1;
-                }
-            }
-            /* We're either at a '{', which means we're starting another
-               expression; or a '}', which means we're at the end of this
-               f-string (for a nested format_spec). */
-            s--;
-            break;
-        }
-    }
-    *str = s;
-    assert(s <= end);
-    assert(s == end || *s == '{' || *s == '}');
-done:
-    if (literal_start != s) {
-        if (raw)
-            *literal = PyUnicode_DecodeUTF8Stateful(literal_start,
-                                                    s - literal_start,
-                                                    NULL, NULL);
-        else
-            *literal = decode_unicode_with_escapes(c, n, literal_start,
-                                                   s - literal_start);
-        if (!*literal)
-            return -1;
-    }
-    return result;
-}
-
-/* Forward declaration because parsing is recursive. */
-static expr_ty
-fstring_parse(const char **str, const char *end, int raw, int recurse_lvl,
-              struct compiling *c, const node *n);
-
-/* Parse the f-string at *str, ending at end.  We know *str starts an
-   expression (so it must be a '{'). Returns the FormattedValue node, which
-   includes the expression, conversion character, format_spec expression, and
-   optionally the text of the expression (if = is used).
-
-   Note that I don't do a perfect job here: I don't make sure that a
-   closing brace doesn't match an opening paren, for example. It
-   doesn't need to error on all invalid expressions, just correctly
-   find the end of all valid ones. Any errors inside the expression
-   will be caught when we parse it later.
-
-   *expression is set to the expression.  For an '=' "debug" expression,
-   *expr_text is set to the debug text (the original text of the expression,
-   including the '=' and any whitespace around it, as a string object).  If
-   not a debug expression, *expr_text set to NULL. */
-static int
-fstring_find_expr(const char **str, const char *end, int raw, int recurse_lvl,
-                  PyObject **expr_text, expr_ty *expression,
-                  struct compiling *c, const node *n)
-{
-    /* Return -1 on error, else 0. */
-
-    const char *expr_start;
-    const char *expr_end;
-    expr_ty simple_expression;
-    expr_ty format_spec = NULL; /* Optional format specifier. */
-    int conversion = -1; /* The conversion char.  Use default if not
-                            specified, or !r if using = and no format
-                            spec. */
-
-    /* 0 if we're not in a string, else the quote char we're trying to
-       match (single or double quote). */
-    char quote_char = 0;
-
-    /* If we're inside a string, 1=normal, 3=triple-quoted. */
-    int string_type = 0;
-
-    /* Keep track of nesting level for braces/parens/brackets in
-       expressions. */
-    Py_ssize_t nested_depth = 0;
-    char parenstack[MAXLEVEL];
-
-    *expr_text = NULL;
-
-    /* Can only nest one level deep. */
-    if (recurse_lvl >= 2) {
-        ast_error(c, n, "f-string: expressions nested too deeply");
-        goto error;
-    }
-
-    /* The first char must be a left brace, or we wouldn't have gotten
-       here. Skip over it. */
-    assert(**str == '{');
-    *str += 1;
-
-    expr_start = *str;
-    for (; *str < end; (*str)++) {
-        char ch;
-
-        /* Loop invariants. */
-        assert(nested_depth >= 0);
-        assert(*str >= expr_start && *str < end);
-        if (quote_char)
-            assert(string_type == 1 || string_type == 3);
-        else
-            assert(string_type == 0);
-
-        ch = **str;
-        /* Nowhere inside an expression is a backslash allowed. */
-        if (ch == '\\') {
-            /* Error: can't include a backslash character, inside
-               parens or strings or not. */
-            ast_error(c, n,
-                      "f-string expression part "
-                      "cannot include a backslash");
-            goto error;
-        }
-        if (quote_char) {
-            /* We're inside a string. See if we're at the end. */
-            /* This code needs to implement the same non-error logic
-               as tok_get from tokenizer.c, at the letter_quote
-               label. To actually share that code would be a
-               nightmare. But, it's unlikely to change and is small,
-               so duplicate it here. Note we don't need to catch all
-               of the errors, since they'll be caught when parsing the
-               expression. We just need to match the non-error
-               cases. Thus we can ignore \n in single-quoted strings,
-               for example. Or non-terminated strings. */
-            if (ch == quote_char) {
-                /* Does this match the string_type (single or triple
-                   quoted)? */
-                if (string_type == 3) {
-                    if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) {
-                        /* We're at the end of a triple quoted string. */
-                        *str += 2;
-                        string_type = 0;
-                        quote_char = 0;
-                        continue;
-                    }
-                } else {
-                    /* We're at the end of a normal string. */
-                    quote_char = 0;
-                    string_type = 0;
-                    continue;
-                }
-            }
-        } else if (ch == '\'' || ch == '"') {
-            /* Is this a triple quoted string? */
-            if (*str+2 < end && *(*str+1) == ch && *(*str+2) == ch) {
-                string_type = 3;
-                *str += 2;
-            } else {
-                /* Start of a normal string. */
-                string_type = 1;
-            }
-            /* Start looking for the end of the string. */
-            quote_char = ch;
-        } else if (ch == '[' || ch == '{' || ch == '(') {
-            if (nested_depth >= MAXLEVEL) {
-                ast_error(c, n, "f-string: too many nested parenthesis");
-                goto error;
-            }
-            parenstack[nested_depth] = ch;
-            nested_depth++;
-        } else if (ch == '#') {
-            /* Error: can't include a comment character, inside parens
-               or not. */
-            ast_error(c, n, "f-string expression part cannot include '#'");
-            goto error;
-        } else if (nested_depth == 0 &&
-                   (ch == '!' || ch == ':' || ch == '}' ||
-                    ch == '=' || ch == '>' || ch == '<')) {
-            /* See if there's a next character. */
-            if (*str+1 < end) {
-                char next = *(*str+1);
-
-                /* For "!=". since '=' is not an allowed conversion character,
-                   nothing is lost in this test. */
-                if ((ch == '!' && next == '=') ||   /* != */
-                    (ch == '=' && next == '=') ||   /* == */
-                    (ch == '<' && next == '=') ||   /* <= */
-                    (ch == '>' && next == '=')      /* >= */
-                    ) {
-                    *str += 1;
-                    continue;
-                }
-                /* Don't get out of the loop for these, if they're single
-                   chars (not part of 2-char tokens). If by themselves, they
-                   don't end an expression (unlike say '!'). */
-                if (ch == '>' || ch == '<') {
-                    continue;
-                }
-            }
-
-            /* Normal way out of this loop. */
-            break;
-        } else if (ch == ']' || ch == '}' || ch == ')') {
-            if (!nested_depth) {
-                ast_error(c, n, "f-string: unmatched '%c'", ch);
-                goto error;
-            }
-            nested_depth--;
-            int opening = parenstack[nested_depth];
-            if (!((opening == '(' && ch == ')') ||
-                  (opening == '[' && ch == ']') ||
-                  (opening == '{' && ch == '}')))
-            {
-                ast_error(c, n,
-                          "f-string: closing parenthesis '%c' "
-                          "does not match opening parenthesis '%c'",
-                          ch, opening);
-                goto error;
-            }
-        } else {
-            /* Just consume this char and loop around. */
-        }
-    }
-    expr_end = *str;
-    /* If we leave this loop in a string or with mismatched parens, we
-       don't care. We'll get a syntax error when compiling the
-       expression. But, we can produce a better error message, so
-       let's just do that.*/
-    if (quote_char) {
-        ast_error(c, n, "f-string: unterminated string");
-        goto error;
-    }
-    if (nested_depth) {
-        int opening = parenstack[nested_depth - 1];
-        ast_error(c, n, "f-string: unmatched '%c'", opening);
-        goto error;
-    }
-
-    if (*str >= end)
-        goto unexpected_end_of_string;
-
-    /* Compile the expression as soon as possible, so we show errors
-       related to the expression before errors related to the
-       conversion or format_spec. */
-    simple_expression = fstring_compile_expr(expr_start, expr_end, c, n);
-    if (!simple_expression)
-        goto error;
-
-    /* Check for =, which puts the text value of the expression in
-       expr_text. */
-    if (**str == '=') {
-        if (c->c_feature_version < 8) {
-            ast_error(c, n,
-                      "f-string: self documenting expressions are "
-                      "only supported in Python 3.8 and greater");
-            goto error;
-        }
-        *str += 1;
-
-        /* Skip over ASCII whitespace.  No need to test for end of string
-           here, since we know there's at least a trailing quote somewhere
-           ahead. */
-        while (Py_ISSPACE(**str)) {
-            *str += 1;
-        }
-
-        /* Set *expr_text to the text of the expression. */
-        *expr_text = PyUnicode_FromStringAndSize(expr_start, *str-expr_start);
-        if (!*expr_text) {
-            goto error;
-        }
-    }
-
-    /* Check for a conversion char, if present. */
-    if (**str == '!') {
-        *str += 1;
-        if (*str >= end)
-            goto unexpected_end_of_string;
-
-        conversion = **str;
-        *str += 1;
-
-        /* Validate the conversion. */
-        if (!(conversion == 's' || conversion == 'r' || conversion == 'a')) {
-            ast_error(c, n,
-                      "f-string: invalid conversion character: "
-                      "expected 's', 'r', or 'a'");
-            goto error;
-        }
-
-    }
-
-    /* Check for the format spec, if present. */
-    if (*str >= end)
-        goto unexpected_end_of_string;
-    if (**str == ':') {
-        *str += 1;
-        if (*str >= end)
-            goto unexpected_end_of_string;
-
-        /* Parse the format spec. */
-        format_spec = fstring_parse(str, end, raw, recurse_lvl+1, c, n);
-        if (!format_spec)
-            goto error;
-    }
-
-    if (*str >= end || **str != '}')
-        goto unexpected_end_of_string;
-
-    /* We're at a right brace. Consume it. */
-    assert(*str < end);
-    assert(**str == '}');
-    *str += 1;
-
-    /* If we're in = mode (detected by non-NULL expr_text), and have no format
-       spec and no explicit conversion, set the conversion to 'r'. */
-    if (*expr_text && format_spec == NULL && conversion == -1) {
-        conversion = 'r';
-    }
-
-    /* And now create the FormattedValue node that represents this
-       entire expression with the conversion and format spec. */
-    *expression = FormattedValue(simple_expression, conversion,
-                                 format_spec, LINENO(n),
-                                 n->n_col_offset, n->n_end_lineno,
-                                 n->n_end_col_offset, c->c_arena);
-    if (!*expression)
-        goto error;
-
-    return 0;
-
-unexpected_end_of_string:
-    ast_error(c, n, "f-string: expecting '}'");
-    /* Falls through to error. */
-
-error:
-    Py_XDECREF(*expr_text);
-    return -1;
-
-}
-
-/* Return -1 on error.
-
-   Return 0 if we have a literal (possible zero length) and an
-   expression (zero length if at the end of the string.
-
-   Return 1 if we have a literal, but no expression, and we want the
-   caller to call us again. This is used to deal with doubled
-   braces.
-
-   When called multiple times on the string 'a{{b{0}c', this function
-   will return:
-
-   1. the literal 'a{' with no expression, and a return value
-      of 1. Despite the fact that there's no expression, the return
-      value of 1 means we're not finished yet.
-
-   2. the literal 'b' and the expression '0', with a return value of
-      0. The fact that there's an expression means we're not finished.
-
-   3. literal 'c' with no expression and a return value of 0. The
-      combination of the return value of 0 with no expression means
-      we're finished.
-*/
-static int
-fstring_find_literal_and_expr(const char **str, const char *end, int raw,
-                              int recurse_lvl, PyObject **literal,
-                              PyObject **expr_text, expr_ty *expression,
-                              struct compiling *c, const node *n)
-{
-    int result;
-
-    assert(*literal == NULL && *expression == NULL);
-
-    /* Get any literal string. */
-    result = fstring_find_literal(str, end, raw, literal, recurse_lvl, c, n);
-    if (result < 0)
-        goto error;
-
-    assert(result == 0 || result == 1);
-
-    if (result == 1)
-        /* We have a literal, but don't look at the expression. */
-        return 1;
-
-    if (*str >= end || **str == '}')
-        /* We're at the end of the string or the end of a nested
-           f-string: no expression. The top-level error case where we
-           expect to be at the end of the string but we're at a '}' is
-           handled later. */
-        return 0;
-
-    /* We must now be the start of an expression, on a '{'. */
-    assert(**str == '{');
-
-    if (fstring_find_expr(str, end, raw, recurse_lvl, expr_text,
-                          expression, c, n) < 0)
-        goto error;
-
-    return 0;
-
-error:
-    Py_CLEAR(*literal);
-    return -1;
-}
-
-#define EXPRLIST_N_CACHED  64
-
-typedef struct {
-    /* Incrementally build an array of expr_ty, so be used in an
-       asdl_seq. Cache some small but reasonably sized number of
-       expr_ty's, and then after that start dynamically allocating,
-       doubling the number allocated each time. Note that the f-string
-       f'{0}a{1}' contains 3 expr_ty's: 2 FormattedValue's, and one
-       Constant for the literal 'a'. So you add expr_ty's about twice as
-       fast as you add expressions in an f-string. */
-
-    Py_ssize_t allocated;  /* Number we've allocated. */
-    Py_ssize_t size;       /* Number we've used. */
-    expr_ty    *p;         /* Pointer to the memory we're actually
-                              using. Will point to 'data' until we
-                              start dynamically allocating. */
-    expr_ty    data[EXPRLIST_N_CACHED];
-} ExprList;
-
-#ifdef NDEBUG
-#define ExprList_check_invariants(l)
-#else
-static void
-ExprList_check_invariants(ExprList *l)
-{
-    /* Check our invariants. Make sure this object is "live", and
-       hasn't been deallocated. */
-    assert(l->size >= 0);
-    assert(l->p != NULL);
-    if (l->size <= EXPRLIST_N_CACHED)
-        assert(l->data == l->p);
-}
-#endif
-
-static void
-ExprList_Init(ExprList *l)
-{
-    l->allocated = EXPRLIST_N_CACHED;
-    l->size = 0;
-
-    /* Until we start allocating dynamically, p points to data. */
-    l->p = l->data;
-
-    ExprList_check_invariants(l);
-}
-
-static int
-ExprList_Append(ExprList *l, expr_ty exp)
-{
-    ExprList_check_invariants(l);
-    if (l->size >= l->allocated) {
-        /* We need to alloc (or realloc) the memory. */
-        Py_ssize_t new_size = l->allocated * 2;
-
-        /* See if we've ever allocated anything dynamically. */
-        if (l->p == l->data) {
-            Py_ssize_t i;
-            /* We're still using the cached data. Switch to
-               alloc-ing. */
-            l->p = PyMem_RawMalloc(sizeof(expr_ty) * new_size);
-            if (!l->p)
-                return -1;
-            /* Copy the cached data into the new buffer. */
-            for (i = 0; i < l->size; i++)
-                l->p[i] = l->data[i];
-        } else {
-            /* Just realloc. */
-            expr_ty *tmp = PyMem_RawRealloc(l->p, sizeof(expr_ty) * new_size);
-            if (!tmp) {
-                PyMem_RawFree(l->p);
-                l->p = NULL;
-                return -1;
-            }
-            l->p = tmp;
-        }
-
-        l->allocated = new_size;
-        assert(l->allocated == 2 * l->size);
-    }
-
-    l->p[l->size++] = exp;
-
-    ExprList_check_invariants(l);
-    return 0;
-}
-
-static void
-ExprList_Dealloc(ExprList *l)
-{
-    ExprList_check_invariants(l);
-
-    /* If there's been an error, or we've never dynamically allocated,
-       do nothing. */
-    if (!l->p || l->p == l->data) {
-        /* Do nothing. */
-    } else {
-        /* We have dynamically allocated. Free the memory. */
-        PyMem_RawFree(l->p);
-    }
-    l->p = NULL;
-    l->size = -1;
-}
-
-static asdl_seq *
-ExprList_Finish(ExprList *l, PyArena *arena)
-{
-    asdl_seq *seq;
-
-    ExprList_check_invariants(l);
-
-    /* Allocate the asdl_seq and copy the expressions in to it. */
-    seq = _Py_asdl_seq_new(l->size, arena);
-    if (seq) {
-        Py_ssize_t i;
-        for (i = 0; i < l->size; i++)
-            asdl_seq_SET(seq, i, l->p[i]);
-    }
-    ExprList_Dealloc(l);
-    return seq;
-}
-
-/* The FstringParser is designed to add a mix of strings and
-   f-strings, and concat them together as needed. Ultimately, it
-   generates an expr_ty. */
-typedef struct {
-    PyObject *last_str;
-    ExprList expr_list;
-    int fmode;
-} FstringParser;
-
-#ifdef NDEBUG
-#define FstringParser_check_invariants(state)
-#else
-static void
-FstringParser_check_invariants(FstringParser *state)
-{
-    if (state->last_str)
-        assert(PyUnicode_CheckExact(state->last_str));
-    ExprList_check_invariants(&state->expr_list);
-}
-#endif
-
-static void
-FstringParser_Init(FstringParser *state)
-{
-    state->last_str = NULL;
-    state->fmode = 0;
-    ExprList_Init(&state->expr_list);
-    FstringParser_check_invariants(state);
-}
-
-static void
-FstringParser_Dealloc(FstringParser *state)
-{
-    FstringParser_check_invariants(state);
-
-    Py_XDECREF(state->last_str);
-    ExprList_Dealloc(&state->expr_list);
-}
-
-/* Constants for the following */
-static PyObject *u_kind;
-
-/* Compute 'kind' field for string Constant (either 'u' or None) */
-static PyObject *
-make_kind(struct compiling *c, const node *n)
-{
-    char *s = NULL;
-    PyObject *kind = NULL;
-
-    /* Find the first string literal, if any */
-    while (TYPE(n) != STRING) {
-        if (NCH(n) == 0)
-            return NULL;
-        n = CHILD(n, 0);
-    }
-    REQ(n, STRING);
-
-    /* If it starts with 'u', return a PyUnicode "u" string */
-    s = STR(n);
-    if (s && *s == 'u') {
-        if (!u_kind) {
-            u_kind = PyUnicode_InternFromString("u");
-            if (!u_kind)
-                return NULL;
-        }
-        kind = u_kind;
-        if (PyArena_AddPyObject(c->c_arena, kind) < 0) {
-            return NULL;
-        }
-        Py_INCREF(kind);
-    }
-    return kind;
-}
-
-/* Make a Constant node, but decref the PyUnicode object being added. */
-static expr_ty
-make_str_node_and_del(PyObject **str, struct compiling *c, const node* n)
-{
-    PyObject *s = *str;
-    PyObject *kind = NULL;
-    *str = NULL;
-    assert(PyUnicode_CheckExact(s));
-    if (PyArena_AddPyObject(c->c_arena, s) < 0) {
-        Py_DECREF(s);
-        return NULL;
-    }
-    kind = make_kind(c, n);
-    if (kind == NULL && PyErr_Occurred())
-        return NULL;
-    return Constant(s, kind, LINENO(n), n->n_col_offset,
-                    n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-}
-
-/* Add a non-f-string (that is, a regular literal string). str is
-   decref'd. */
-static int
-FstringParser_ConcatAndDel(FstringParser *state, PyObject *str)
-{
-    FstringParser_check_invariants(state);
-
-    assert(PyUnicode_CheckExact(str));
-
-    if (PyUnicode_GET_LENGTH(str) == 0) {
-        Py_DECREF(str);
-        return 0;
-    }
-
-    if (!state->last_str) {
-        /* We didn't have a string before, so just remember this one. */
-        state->last_str = str;
-    } else {
-        /* Concatenate this with the previous string. */
-        PyUnicode_AppendAndDel(&state->last_str, str);
-        if (!state->last_str)
-            return -1;
-    }
-    FstringParser_check_invariants(state);
-    return 0;
-}
-
-/* Parse an f-string. The f-string is in *str to end, with no
-   'f' or quotes. */
-static int
-FstringParser_ConcatFstring(FstringParser *state, const char **str,
-                            const char *end, int raw, int recurse_lvl,
-                            struct compiling *c, const node *n)
-{
-    FstringParser_check_invariants(state);
-    state->fmode = 1;
-
-    /* Parse the f-string. */
-    while (1) {
-        PyObject *literal = NULL;
-        PyObject *expr_text = NULL;
-        expr_ty expression = NULL;
-
-        /* If there's a zero length literal in front of the
-           expression, literal will be NULL. If we're at the end of
-           the f-string, expression will be NULL (unless result == 1,
-           see below). */
-        int result = fstring_find_literal_and_expr(str, end, raw, recurse_lvl,
-                                                   &literal, &expr_text,
-                                                   &expression, c, n);
-        if (result < 0)
-            return -1;
-
-        /* Add the literal, if any. */
-        if (literal && FstringParser_ConcatAndDel(state, literal) < 0) {
-            Py_XDECREF(expr_text);
-            return -1;
-        }
-        /* Add the expr_text, if any. */
-        if (expr_text && FstringParser_ConcatAndDel(state, expr_text) < 0) {
-            return -1;
-        }
-
-        /* We've dealt with the literal and expr_text, their ownership has
-           been transferred to the state object.  Don't look at them again. */
-
-        /* See if we should just loop around to get the next literal
-           and expression, while ignoring the expression this
-           time. This is used for un-doubling braces, as an
-           optimization. */
-        if (result == 1)
-            continue;
-
-        if (!expression)
-            /* We're done with this f-string. */
-            break;
-
-        /* We know we have an expression. Convert any existing string
-           to a Constant node. */
-        if (!state->last_str) {
-            /* Do nothing. No previous literal. */
-        } else {
-            /* Convert the existing last_str literal to a Constant node. */
-            expr_ty str = make_str_node_and_del(&state->last_str, c, n);
-            if (!str || ExprList_Append(&state->expr_list, str) < 0)
-                return -1;
-        }
-
-        if (ExprList_Append(&state->expr_list, expression) < 0)
-            return -1;
-    }
-
-    /* If recurse_lvl is zero, then we must be at the end of the
-       string. Otherwise, we must be at a right brace. */
-
-    if (recurse_lvl == 0 && *str < end-1) {
-        ast_error(c, n, "f-string: unexpected end of string");
-        return -1;
-    }
-    if (recurse_lvl != 0 && **str != '}') {
-        ast_error(c, n, "f-string: expecting '}'");
-        return -1;
-    }
-
-    FstringParser_check_invariants(state);
-    return 0;
-}
-
-/* Convert the partial state reflected in last_str and expr_list to an
-   expr_ty. The expr_ty can be a Constant, or a JoinedStr. */
-static expr_ty
-FstringParser_Finish(FstringParser *state, struct compiling *c,
-                     const node *n)
-{
-    asdl_seq *seq;
-
-    FstringParser_check_invariants(state);
-
-    /* If we're just a constant string with no expressions, return
-       that. */
-    if (!state->fmode) {
-        assert(!state->expr_list.size);
-        if (!state->last_str) {
-            /* Create a zero length string. */
-            state->last_str = PyUnicode_FromStringAndSize(NULL, 0);
-            if (!state->last_str)
-                goto error;
-        }
-        return make_str_node_and_del(&state->last_str, c, n);
-    }
-
-    /* Create a Constant node out of last_str, if needed. It will be the
-       last node in our expression list. */
-    if (state->last_str) {
-        expr_ty str = make_str_node_and_del(&state->last_str, c, n);
-        if (!str || ExprList_Append(&state->expr_list, str) < 0)
-            goto error;
-    }
-    /* This has already been freed. */
-    assert(state->last_str == NULL);
-
-    seq = ExprList_Finish(&state->expr_list, c->c_arena);
-    if (!seq)
-        goto error;
-
-    return JoinedStr(seq, LINENO(n), n->n_col_offset,
-                     n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-
-error:
-    FstringParser_Dealloc(state);
-    return NULL;
-}
-
-/* Given an f-string (with no 'f' or quotes) that's in *str and ends
-   at end, parse it into an expr_ty.  Return NULL on error.  Adjust
-   str to point past the parsed portion. */
-static expr_ty
-fstring_parse(const char **str, const char *end, int raw, int recurse_lvl,
-              struct compiling *c, const node *n)
-{
-    FstringParser state;
-
-    FstringParser_Init(&state);
-    if (FstringParser_ConcatFstring(&state, str, end, raw, recurse_lvl,
-                                    c, n) < 0) {
-        FstringParser_Dealloc(&state);
-        return NULL;
-    }
-
-    return FstringParser_Finish(&state, c, n);
-}
-
-/* n is a Python string literal, including the bracketing quote
-   characters, and r, b, u, &/or f prefixes (if any), and embedded
-   escape sequences (if any). parsestr parses it, and sets *result to
-   decoded Python string object.  If the string is an f-string, set
-   *fstr and *fstrlen to the unparsed string object.  Return 0 if no
-   errors occurred.
-*/
-static int
-parsestr(struct compiling *c, const node *n, int *bytesmode, int *rawmode,
-         PyObject **result, const char **fstr, Py_ssize_t *fstrlen)
-{
-    size_t len;
-    const char *s = STR(n);
-    int quote = Py_CHARMASK(*s);
-    int fmode = 0;
-    *bytesmode = 0;
-    *rawmode = 0;
-    *result = NULL;
-    *fstr = NULL;
-    if (Py_ISALPHA(quote)) {
-        while (!*bytesmode || !*rawmode) {
-            if (quote == 'b' || quote == 'B') {
-                quote = *++s;
-                *bytesmode = 1;
-            }
-            else if (quote == 'u' || quote == 'U') {
-                quote = *++s;
-            }
-            else if (quote == 'r' || quote == 'R') {
-                quote = *++s;
-                *rawmode = 1;
-            }
-            else if (quote == 'f' || quote == 'F') {
-                quote = *++s;
-                fmode = 1;
-            }
-            else {
-                break;
-            }
-        }
-    }
-
-    /* fstrings are only allowed in Python 3.6 and greater */
-    if (fmode && c->c_feature_version < 6) {
-        ast_error(c, n, "Format strings are only supported in Python 3.6 and greater");
-        return -1;
-    }
-
-    if (fmode && *bytesmode) {
-        PyErr_BadInternalCall();
-        return -1;
-    }
-    if (quote != '\'' && quote != '\"') {
-        PyErr_BadInternalCall();
-        return -1;
-    }
-    /* Skip the leading quote char. */
-    s++;
-    len = strlen(s);
-    if (len > INT_MAX) {
-        PyErr_SetString(PyExc_OverflowError,
-                        "string to parse is too long");
-        return -1;
-    }
-    if (s[--len] != quote) {
-        /* Last quote char must match the first. */
-        PyErr_BadInternalCall();
-        return -1;
-    }
-    if (len >= 4 && s[0] == quote && s[1] == quote) {
-        /* A triple quoted string. We've already skipped one quote at
-           the start and one at the end of the string. Now skip the
-           two at the start. */
-        s += 2;
-        len -= 2;
-        /* And check that the last two match. */
-        if (s[--len] != quote || s[--len] != quote) {
-            PyErr_BadInternalCall();
-            return -1;
-        }
-    }
-
-    if (fmode) {
-        /* Just return the bytes. The caller will parse the resulting
-           string. */
-        *fstr = s;
-        *fstrlen = len;
-        return 0;
-    }
-
-    /* Not an f-string. */
-    /* Avoid invoking escape decoding routines if possible. */
-    *rawmode = *rawmode || strchr(s, '\\') == NULL;
-    if (*bytesmode) {
-        /* Disallow non-ASCII characters. */
-        const char *ch;
-        for (ch = s; *ch; ch++) {
-            if (Py_CHARMASK(*ch) >= 0x80) {
-                ast_error(c, n,
-                          "bytes can only contain ASCII "
-                          "literal characters.");
-                return -1;
-            }
-        }
-        if (*rawmode)
-            *result = PyBytes_FromStringAndSize(s, len);
-        else
-            *result = decode_bytes_with_escapes(c, n, s, len);
-    } else {
-        if (*rawmode)
-            *result = PyUnicode_DecodeUTF8Stateful(s, len, NULL, NULL);
-        else
-            *result = decode_unicode_with_escapes(c, n, s, len);
-    }
-    return *result == NULL ? -1 : 0;
-}
-
-/* Accepts a STRING+ atom, and produces an expr_ty node. Run through
-   each STRING atom, and process it as needed. For bytes, just
-   concatenate them together, and the result will be a Constant node. For
-   normal strings and f-strings, concatenate them together. The result
-   will be a Constant node if there were no f-strings; a FormattedValue
-   node if there's just an f-string (with no leading or trailing
-   literals), or a JoinedStr node if there are multiple f-strings or
-   any literals involved. */
-static expr_ty
-parsestrplus(struct compiling *c, const node *n)
-{
-    int bytesmode = 0;
-    PyObject *bytes_str = NULL;
-    int i;
-
-    FstringParser state;
-    FstringParser_Init(&state);
-
-    for (i = 0; i < NCH(n); i++) {
-        int this_bytesmode;
-        int this_rawmode;
-        PyObject *s;
-        const char *fstr;
-        Py_ssize_t fstrlen = -1;  /* Silence a compiler warning. */
-
-        REQ(CHILD(n, i), STRING);
-        if (parsestr(c, CHILD(n, i), &this_bytesmode, &this_rawmode, &s,
-                     &fstr, &fstrlen) != 0)
-            goto error;
-
-        /* Check that we're not mixing bytes with unicode. */
-        if (i != 0 && bytesmode != this_bytesmode) {
-            ast_error(c, n, "cannot mix bytes and nonbytes literals");
-            /* s is NULL if the current string part is an f-string. */
-            Py_XDECREF(s);
-            goto error;
-        }
-        bytesmode = this_bytesmode;
-
-        if (fstr != NULL) {
-            int result;
-            assert(s == NULL && !bytesmode);
-            /* This is an f-string. Parse and concatenate it. */
-            result = FstringParser_ConcatFstring(&state, &fstr, fstr+fstrlen,
-                                                 this_rawmode, 0, c, n);
-            if (result < 0)
-                goto error;
-        } else {
-            /* A string or byte string. */
-            assert(s != NULL && fstr == NULL);
-
-            assert(bytesmode ? PyBytes_CheckExact(s) :
-                   PyUnicode_CheckExact(s));
-
-            if (bytesmode) {
-                /* For bytes, concat as we go. */
-                if (i == 0) {
-                    /* First time, just remember this value. */
-                    bytes_str = s;
-                } else {
-                    PyBytes_ConcatAndDel(&bytes_str, s);
-                    if (!bytes_str)
-                        goto error;
-                }
-            } else {
-                /* This is a regular string. Concatenate it. */
-                if (FstringParser_ConcatAndDel(&state, s) < 0)
-                    goto error;
-            }
-        }
-    }
-    if (bytesmode) {
-        /* Just return the bytes object and we're done. */
-        if (PyArena_AddPyObject(c->c_arena, bytes_str) < 0)
-            goto error;
-        return Constant(bytes_str, NULL, LINENO(n), n->n_col_offset,
-                        n->n_end_lineno, n->n_end_col_offset, c->c_arena);
-    }
-
-    /* We're not a bytes string, bytes_str should never have been set. */
-    assert(bytes_str == NULL);
-
-    return FstringParser_Finish(&state, c, n);
-
-error:
-    Py_XDECREF(bytes_str);
-    FstringParser_Dealloc(&state);
-    return NULL;
-}
-
 PyObject *
 _PyAST_GetDocString(asdl_seq *body)
 {