bpo-29463: Add docstring field to some AST nodes. (#46)

* bpo-29463: Add docstring field to some AST nodes.

ClassDef, ModuleDef, FunctionDef, and AsyncFunctionDef has docstring
field for now.  It was first statement of there body.

* fix document.  thanks travis!

* doc fixes

1 files changed, 1 insertions, 9 deletions

diff --git a/Lib/ast.py b/Lib/ast.py
index 156a1f2..0729ee7 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -197,15 +197,7 @@ def get_docstring(node, clean=True):
     """
     if not isinstance(node, (AsyncFunctionDef, FunctionDef, ClassDef, Module)):
         raise TypeError("%r can't have docstrings" % node.__class__.__name__)
-    if not(node.body and isinstance(node.body[0], Expr)):
-        return
-    node = node.body[0].value
-    if isinstance(node, Str):
-        text = node.s
-    elif isinstance(node, Constant) and isinstance(node.value, str):
-        text = node.value
-    else:
-        return
+    text = node.docstring
     if clean:
         import inspect
         text = inspect.cleandoc(text)