GH-84976: Move Lib/datetime.py to Lib/_pydatetime

This breaks the tests, but we are keeping it as a separate commit so
that the move operation and editing of the moved files are separate, for
a cleaner history.

1 files changed, 2663 insertions, 0 deletions

diff --git a/Lib/_pydatetime.py b/Lib/_pydatetime.py
new file mode 100644
index 0000000..b0eb1c2
--- /dev/null
+++ b/Lib/_pydatetime.py
@@ -0,0 +1,2663 @@
+"""Concrete date/time and related types.
+
+See http://www.iana.org/time-zones/repository/tz-link.html for
+time zone and DST data sources.
+"""
+
+__all__ = ("date", "datetime", "time", "timedelta", "timezone", "tzinfo",
+           "MINYEAR", "MAXYEAR", "UTC")
+
+
+import time as _time
+import math as _math
+import sys
+from operator import index as _index
+
+def _cmp(x, y):
+    return 0 if x == y else 1 if x > y else -1
+
+MINYEAR = 1
+MAXYEAR = 9999
+_MAXORDINAL = 3652059  # date.max.toordinal()
+
+# Utility functions, adapted from Python's Demo/classes/Dates.py, which
+# also assumes the current Gregorian calendar indefinitely extended in
+# both directions.  Difference:  Dates.py calls January 1 of year 0 day
+# number 1.  The code here calls January 1 of year 1 day number 1.  This is
+# to match the definition of the "proleptic Gregorian" calendar in Dershowitz
+# and Reingold's "Calendrical Calculations", where it's the base calendar
+# for all computations.  See the book for algorithms for converting between
+# proleptic Gregorian ordinals and many other calendar systems.
+
+# -1 is a placeholder for indexing purposes.
+_DAYS_IN_MONTH = [-1, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+
+_DAYS_BEFORE_MONTH = [-1]  # -1 is a placeholder for indexing purposes.
+dbm = 0
+for dim in _DAYS_IN_MONTH[1:]:
+    _DAYS_BEFORE_MONTH.append(dbm)
+    dbm += dim
+del dbm, dim
+
+def _is_leap(year):
+    "year -> 1 if leap year, else 0."
+    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)
+
+def _days_before_year(year):
+    "year -> number of days before January 1st of year."
+    y = year - 1
+    return y*365 + y//4 - y//100 + y//400
+
+def _days_in_month(year, month):
+    "year, month -> number of days in that month in that year."
+    assert 1 <= month <= 12, month
+    if month == 2 and _is_leap(year):
+        return 29
+    return _DAYS_IN_MONTH[month]
+
+def _days_before_month(year, month):
+    "year, month -> number of days in year preceding first day of month."
+    assert 1 <= month <= 12, 'month must be in 1..12'
+    return _DAYS_BEFORE_MONTH[month] + (month > 2 and _is_leap(year))
+
+def _ymd2ord(year, month, day):
+    "year, month, day -> ordinal, considering 01-Jan-0001 as day 1."
+    assert 1 <= month <= 12, 'month must be in 1..12'
+    dim = _days_in_month(year, month)
+    assert 1 <= day <= dim, ('day must be in 1..%d' % dim)
+    return (_days_before_year(year) +
+            _days_before_month(year, month) +
+            day)
+
+_DI400Y = _days_before_year(401)    # number of days in 400 years
+_DI100Y = _days_before_year(101)    #    "    "   "   " 100   "
+_DI4Y   = _days_before_year(5)      #    "    "   "   "   4   "
+
+# A 4-year cycle has an extra leap day over what we'd get from pasting
+# together 4 single years.
+assert _DI4Y == 4 * 365 + 1
+
+# Similarly, a 400-year cycle has an extra leap day over what we'd get from
+# pasting together 4 100-year cycles.
+assert _DI400Y == 4 * _DI100Y + 1
+
+# OTOH, a 100-year cycle has one fewer leap day than we'd get from
+# pasting together 25 4-year cycles.
+assert _DI100Y == 25 * _DI4Y - 1
+
+def _ord2ymd(n):
+    "ordinal -> (year, month, day), considering 01-Jan-0001 as day 1."
+
+    # n is a 1-based index, starting at 1-Jan-1.  The pattern of leap years
+    # repeats exactly every 400 years.  The basic strategy is to find the
+    # closest 400-year boundary at or before n, then work with the offset
+    # from that boundary to n.  Life is much clearer if we subtract 1 from
+    # n first -- then the values of n at 400-year boundaries are exactly
+    # those divisible by _DI400Y:
+    #
+    #     D  M   Y            n              n-1
+    #     -- --- ----        ----------     ----------------
+    #     31 Dec -400        -_DI400Y       -_DI400Y -1
+    #      1 Jan -399         -_DI400Y +1   -_DI400Y      400-year boundary
+    #     ...
+    #     30 Dec  000        -1             -2
+    #     31 Dec  000         0             -1
+    #      1 Jan  001         1              0            400-year boundary
+    #      2 Jan  001         2              1
+    #      3 Jan  001         3              2
+    #     ...
+    #     31 Dec  400         _DI400Y        _DI400Y -1
+    #      1 Jan  401         _DI400Y +1     _DI400Y      400-year boundary
+    n -= 1
+    n400, n = divmod(n, _DI400Y)
+    year = n400 * 400 + 1   # ..., -399, 1, 401, ...
+
+    # Now n is the (non-negative) offset, in days, from January 1 of year, to
+    # the desired date.  Now compute how many 100-year cycles precede n.
+    # Note that it's possible for n100 to equal 4!  In that case 4 full
+    # 100-year cycles precede the desired day, which implies the desired
+    # day is December 31 at the end of a 400-year cycle.
+    n100, n = divmod(n, _DI100Y)
+
+    # Now compute how many 4-year cycles precede it.
+    n4, n = divmod(n, _DI4Y)
+
+    # And now how many single years.  Again n1 can be 4, and again meaning
+    # that the desired day is December 31 at the end of the 4-year cycle.
+    n1, n = divmod(n, 365)
+
+    year += n100 * 100 + n4 * 4 + n1
+    if n1 == 4 or n100 == 4:
+        assert n == 0
+        return year-1, 12, 31
+
+    # Now the year is correct, and n is the offset from January 1.  We find
+    # the month via an estimate that's either exact or one too large.
+    leapyear = n1 == 3 and (n4 != 24 or n100 == 3)
+    assert leapyear == _is_leap(year)
+    month = (n + 50) >> 5
+    preceding = _DAYS_BEFORE_MONTH[month] + (month > 2 and leapyear)
+    if preceding > n:  # estimate is too large
+        month -= 1
+        preceding -= _DAYS_IN_MONTH[month] + (month == 2 and leapyear)
+    n -= preceding
+    assert 0 <= n < _days_in_month(year, month)
+
+    # Now the year and month are correct, and n is the offset from the
+    # start of that month:  we're done!
+    return year, month, n+1
+
+# Month and day names.  For localized versions, see the calendar module.
+_MONTHNAMES = [None, "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+                     "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
+_DAYNAMES = [None, "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
+
+
+def _build_struct_time(y, m, d, hh, mm, ss, dstflag):
+    wday = (_ymd2ord(y, m, d) + 6) % 7
+    dnum = _days_before_month(y, m) + d
+    return _time.struct_time((y, m, d, hh, mm, ss, wday, dnum, dstflag))
+
+def _format_time(hh, mm, ss, us, timespec='auto'):
+    specs = {
+        'hours': '{:02d}',
+        'minutes': '{:02d}:{:02d}',
+        'seconds': '{:02d}:{:02d}:{:02d}',
+        'milliseconds': '{:02d}:{:02d}:{:02d}.{:03d}',
+        'microseconds': '{:02d}:{:02d}:{:02d}.{:06d}'
+    }
+
+    if timespec == 'auto':
+        # Skip trailing microseconds when us==0.
+        timespec = 'microseconds' if us else 'seconds'
+    elif timespec == 'milliseconds':
+        us //= 1000
+    try:
+        fmt = specs[timespec]
+    except KeyError:
+        raise ValueError('Unknown timespec value')
+    else:
+        return fmt.format(hh, mm, ss, us)
+
+def _format_offset(off, sep=':'):
+    s = ''
+    if off is not None:
+        if off.days < 0:
+            sign = "-"
+            off = -off
+        else:
+            sign = "+"
+        hh, mm = divmod(off, timedelta(hours=1))
+        mm, ss = divmod(mm, timedelta(minutes=1))
+        s += "%s%02d%s%02d" % (sign, hh, sep, mm)
+        if ss or ss.microseconds:
+            s += "%s%02d" % (sep, ss.seconds)
+
+            if ss.microseconds:
+                s += '.%06d' % ss.microseconds
+    return s
+
+# Correctly substitute for %z and %Z escapes in strftime formats.
+def _wrap_strftime(object, format, timetuple):
+    # Don't call utcoffset() or tzname() unless actually needed.
+    freplace = None  # the string to use for %f
+    zreplace = None  # the string to use for %z
+    colonzreplace = None  # the string to use for %:z
+    Zreplace = None  # the string to use for %Z
+
+    # Scan format for %z, %:z and %Z escapes, replacing as needed.
+    newformat = []
+    push = newformat.append
+    i, n = 0, len(format)
+    while i < n:
+        ch = format[i]
+        i += 1
+        if ch == '%':
+            if i < n:
+                ch = format[i]
+                i += 1
+                if ch == 'f':
+                    if freplace is None:
+                        freplace = '%06d' % getattr(object,
+                                                    'microsecond', 0)
+                    newformat.append(freplace)
+                elif ch == 'z':
+                    if zreplace is None:
+                        if hasattr(object, "utcoffset"):
+                            zreplace = _format_offset(object.utcoffset(), sep="")
+                        else:
+                            zreplace = ""
+                    assert '%' not in zreplace
+                    newformat.append(zreplace)
+                elif ch == ':':
+                    if i < n:
+                        ch2 = format[i]
+                        i += 1
+                        if ch2 == 'z':
+                            if colonzreplace is None:
+                                if hasattr(object, "utcoffset"):
+                                    colonzreplace = _format_offset(object.utcoffset(), sep=":")
+                                else:
+                                    colonzreplace = ""
+                            assert '%' not in colonzreplace
+                            newformat.append(colonzreplace)
+                        else:
+                            push('%')
+                            push(ch)
+                            push(ch2)
+                elif ch == 'Z':
+                    if Zreplace is None:
+                        Zreplace = ""
+                        if hasattr(object, "tzname"):
+                            s = object.tzname()
+                            if s is not None:
+                                # strftime is going to have at this: escape %
+                                Zreplace = s.replace('%', '%%')
+                    newformat.append(Zreplace)
+                else:
+                    push('%')
+                    push(ch)
+            else:
+                push('%')
+        else:
+            push(ch)
+    newformat = "".join(newformat)
+    return _time.strftime(newformat, timetuple)
+
+# Helpers for parsing the result of isoformat()
+def _is_ascii_digit(c):
+    return c in "0123456789"
+
+def _find_isoformat_datetime_separator(dtstr):
+    # See the comment in _datetimemodule.c:_find_isoformat_datetime_separator
+    len_dtstr = len(dtstr)
+    if len_dtstr == 7:
+        return 7
+
+    assert len_dtstr > 7
+    date_separator = "-"
+    week_indicator = "W"
+
+    if dtstr[4] == date_separator:
+        if dtstr[5] == week_indicator:
+            if len_dtstr < 8:
+                raise ValueError("Invalid ISO string")
+            if len_dtstr > 8 and dtstr[8] == date_separator:
+                if len_dtstr == 9:
+                    raise ValueError("Invalid ISO string")
+                if len_dtstr > 10 and _is_ascii_digit(dtstr[10]):
+                    # This is as far as we need to resolve the ambiguity for
+                    # the moment - if we have YYYY-Www-##, the separator is
+                    # either a hyphen at 8 or a number at 10.
+                    #
+                    # We'll assume it's a hyphen at 8 because it's way more
+                    # likely that someone will use a hyphen as a separator than
+                    # a number, but at this point it's really best effort
+                    # because this is an extension of the spec anyway.
+                    # TODO(pganssle): Document this
+                    return 8
+                return 10
+            else:
+                # YYYY-Www (8)
+                return 8
+        else:
+            # YYYY-MM-DD (10)
+            return 10
+    else:
+        if dtstr[4] == week_indicator:
+            # YYYYWww (7) or YYYYWwwd (8)
+            idx = 7
+            while idx < len_dtstr:
+                if not _is_ascii_digit(dtstr[idx]):
+                    break
+                idx += 1
+
+            if idx < 9:
+                return idx
+
+            if idx % 2 == 0:
+                # If the index of the last number is even, it's YYYYWwwd
+                return 7
+            else:
+                return 8
+        else:
+            # YYYYMMDD (8)
+            return 8
+
+
+def _parse_isoformat_date(dtstr):
+    # It is assumed that this is an ASCII-only string of lengths 7, 8 or 10,
+    # see the comment on Modules/_datetimemodule.c:_find_isoformat_datetime_separator
+    assert len(dtstr) in (7, 8, 10)
+    year = int(dtstr[0:4])
+    has_sep = dtstr[4] == '-'
+
+    pos = 4 + has_sep
+    if dtstr[pos:pos + 1] == "W":
+        # YYYY-?Www-?D?
+        pos += 1
+        weekno = int(dtstr[pos:pos + 2])
+        pos += 2
+
+        dayno = 1
+        if len(dtstr) > pos:
+            if (dtstr[pos:pos + 1] == '-') != has_sep:
+                raise ValueError("Inconsistent use of dash separator")
+
+            pos += has_sep
+
+            dayno = int(dtstr[pos:pos + 1])
+
+        return list(_isoweek_to_gregorian(year, weekno, dayno))
+    else:
+        month = int(dtstr[pos:pos + 2])
+        pos += 2
+        if (dtstr[pos:pos + 1] == "-") != has_sep:
+            raise ValueError("Inconsistent use of dash separator")
+
+        pos += has_sep
+        day = int(dtstr[pos:pos + 2])
+
+        return [year, month, day]
+
+
+_FRACTION_CORRECTION = [100000, 10000, 1000, 100, 10]
+
+
+def _parse_hh_mm_ss_ff(tstr):
+    # Parses things of the form HH[:?MM[:?SS[{.,}fff[fff]]]]
+    len_str = len(tstr)
+
+    time_comps = [0, 0, 0, 0]
+    pos = 0
+    for comp in range(0, 3):
+        if (len_str - pos) < 2:
+            raise ValueError("Incomplete time component")
+
+        time_comps[comp] = int(tstr[pos:pos+2])
+
+        pos += 2
+        next_char = tstr[pos:pos+1]
+
+        if comp == 0:
+            has_sep = next_char == ':'
+
+        if not next_char or comp >= 2:
+            break
+
+        if has_sep and next_char != ':':
+            raise ValueError("Invalid time separator: %c" % next_char)
+
+        pos += has_sep
+
+    if pos < len_str:
+        if tstr[pos] not in '.,':
+            raise ValueError("Invalid microsecond component")
+        else:
+            pos += 1
+
+            len_remainder = len_str - pos
+
+            if len_remainder >= 6:
+                to_parse = 6
+            else:
+                to_parse = len_remainder
+
+            time_comps[3] = int(tstr[pos:(pos+to_parse)])
+            if to_parse < 6:
+                time_comps[3] *= _FRACTION_CORRECTION[to_parse-1]
+            if (len_remainder > to_parse
+                    and not all(map(_is_ascii_digit, tstr[(pos+to_parse):]))):
+                raise ValueError("Non-digit values in unparsed fraction")
+
+    return time_comps
+
+def _parse_isoformat_time(tstr):
+    # Format supported is HH[:MM[:SS[.fff[fff]]]][+HH:MM[:SS[.ffffff]]]
+    len_str = len(tstr)
+    if len_str < 2:
+        raise ValueError("Isoformat time too short")
+
+    # This is equivalent to re.search('[+-Z]', tstr), but faster
+    tz_pos = (tstr.find('-') + 1 or tstr.find('+') + 1 or tstr.find('Z') + 1)
+    timestr = tstr[:tz_pos-1] if tz_pos > 0 else tstr
+
+    time_comps = _parse_hh_mm_ss_ff(timestr)
+
+    tzi = None
+    if tz_pos == len_str and tstr[-1] == 'Z':
+        tzi = timezone.utc
+    elif tz_pos > 0:
+        tzstr = tstr[tz_pos:]
+
+        # Valid time zone strings are:
+        # HH                  len: 2
+        # HHMM                len: 4
+        # HH:MM               len: 5
+        # HHMMSS              len: 6
+        # HHMMSS.f+           len: 7+
+        # HH:MM:SS            len: 8
+        # HH:MM:SS.f+         len: 10+
+
+        if len(tzstr) in (0, 1, 3):
+            raise ValueError("Malformed time zone string")
+
+        tz_comps = _parse_hh_mm_ss_ff(tzstr)
+
+        if all(x == 0 for x in tz_comps):
+            tzi = timezone.utc
+        else:
+            tzsign = -1 if tstr[tz_pos - 1] == '-' else 1
+
+            td = timedelta(hours=tz_comps[0], minutes=tz_comps[1],
+                           seconds=tz_comps[2], microseconds=tz_comps[3])
+
+            tzi = timezone(tzsign * td)
+
+    time_comps.append(tzi)
+
+    return time_comps
+
+# tuple[int, int, int] -> tuple[int, int, int] version of date.fromisocalendar
+def _isoweek_to_gregorian(year, week, day):
+    # Year is bounded this way because 9999-12-31 is (9999, 52, 5)
+    if not MINYEAR <= year <= MAXYEAR:
+        raise ValueError(f"Year is out of range: {year}")
+
+    if not 0 < week < 53:
+        out_of_range = True
+
+        if week == 53:
+            # ISO years have 53 weeks in them on years starting with a
+            # Thursday and leap years starting on a Wednesday
+            first_weekday = _ymd2ord(year, 1, 1) % 7
+            if (first_weekday == 4 or (first_weekday == 3 and
+                                       _is_leap(year))):
+                out_of_range = False
+
+        if out_of_range:
+            raise ValueError(f"Invalid week: {week}")
+
+    if not 0 < day < 8:
+        raise ValueError(f"Invalid weekday: {day} (range is [1, 7])")
+
+    # Now compute the offset from (Y, 1, 1) in days:
+    day_offset = (week - 1) * 7 + (day - 1)
+
+    # Calculate the ordinal day for monday, week 1
+    day_1 = _isoweek1monday(year)
+    ord_day = day_1 + day_offset
+
+    return _ord2ymd(ord_day)
+
+
+# Just raise TypeError if the arg isn't None or a string.
+def _check_tzname(name):
+    if name is not None and not isinstance(name, str):
+        raise TypeError("tzinfo.tzname() must return None or string, "
+                        "not '%s'" % type(name))
+
+# name is the offset-producing method, "utcoffset" or "dst".
+# offset is what it returned.
+# If offset isn't None or timedelta, raises TypeError.
+# If offset is None, returns None.
+# Else offset is checked for being in range.
+# If it is, its integer value is returned.  Else ValueError is raised.
+def _check_utc_offset(name, offset):
+    assert name in ("utcoffset", "dst")
+    if offset is None:
+        return
+    if not isinstance(offset, timedelta):
+        raise TypeError("tzinfo.%s() must return None "
+                        "or timedelta, not '%s'" % (name, type(offset)))
+    if not -timedelta(1) < offset < timedelta(1):
+        raise ValueError("%s()=%s, must be strictly between "
+                         "-timedelta(hours=24) and timedelta(hours=24)" %
+                         (name, offset))
+
+def _check_date_fields(year, month, day):
+    year = _index(year)
+    month = _index(month)
+    day = _index(day)
+    if not MINYEAR <= year <= MAXYEAR:
+        raise ValueError('year must be in %d..%d' % (MINYEAR, MAXYEAR), year)
+    if not 1 <= month <= 12:
+        raise ValueError('month must be in 1..12', month)
+    dim = _days_in_month(year, month)
+    if not 1 <= day <= dim:
+        raise ValueError('day must be in 1..%d' % dim, day)
+    return year, month, day
+
+def _check_time_fields(hour, minute, second, microsecond, fold):
+    hour = _index(hour)
+    minute = _index(minute)
+    second = _index(second)
+    microsecond = _index(microsecond)
+    if not 0 <= hour <= 23:
+        raise ValueError('hour must be in 0..23', hour)
+    if not 0 <= minute <= 59:
+        raise ValueError('minute must be in 0..59', minute)
+    if not 0 <= second <= 59:
+        raise ValueError('second must be in 0..59', second)
+    if not 0 <= microsecond <= 999999:
+        raise ValueError('microsecond must be in 0..999999', microsecond)
+    if fold not in (0, 1):
+        raise ValueError('fold must be either 0 or 1', fold)
+    return hour, minute, second, microsecond, fold
+
+def _check_tzinfo_arg(tz):
+    if tz is not None and not isinstance(tz, tzinfo):
+        raise TypeError("tzinfo argument must be None or of a tzinfo subclass")
+
+def _cmperror(x, y):
+    raise TypeError("can't compare '%s' to '%s'" % (
+                    type(x).__name__, type(y).__name__))
+
+def _divide_and_round(a, b):
+    """divide a by b and round result to the nearest integer
+
+    When the ratio is exactly half-way between two integers,
+    the even integer is returned.
+    """
+    # Based on the reference implementation for divmod_near
+    # in Objects/longobject.c.
+    q, r = divmod(a, b)
+    # round up if either r / b > 0.5, or r / b == 0.5 and q is odd.
+    # The expression r / b > 0.5 is equivalent to 2 * r > b if b is
+    # positive, 2 * r < b if b negative.
+    r *= 2
+    greater_than_half = r > b if b > 0 else r < b
+    if greater_than_half or r == b and q % 2 == 1:
+        q += 1
+
+    return q
+
+
+class timedelta:
+    """Represent the difference between two datetime objects.
+
+    Supported operators:
+
+    - add, subtract timedelta
+    - unary plus, minus, abs
+    - compare to timedelta
+    - multiply, divide by int
+
+    In addition, datetime supports subtraction of two datetime objects
+    returning a timedelta, and addition or subtraction of a datetime
+    and a timedelta giving a datetime.
+
+    Representation: (days, seconds, microseconds).
+    """
+    # The representation of (days, seconds, microseconds) was chosen
+    # arbitrarily; the exact rationale originally specified in the docstring
+    # was "Because I felt like it."
+
+    __slots__ = '_days', '_seconds', '_microseconds', '_hashcode'
+
+    def __new__(cls, days=0, seconds=0, microseconds=0,
+                milliseconds=0, minutes=0, hours=0, weeks=0):
+        # Doing this efficiently and accurately in C is going to be difficult
+        # and error-prone, due to ubiquitous overflow possibilities, and that
+        # C double doesn't have enough bits of precision to represent
+        # microseconds over 10K years faithfully.  The code here tries to make
+        # explicit where go-fast assumptions can be relied on, in order to
+        # guide the C implementation; it's way more convoluted than speed-
+        # ignoring auto-overflow-to-long idiomatic Python could be.
+
+        # XXX Check that all inputs are ints or floats.
+
+        # Final values, all integer.
+        # s and us fit in 32-bit signed ints; d isn't bounded.
+        d = s = us = 0
+
+        # Normalize everything to days, seconds, microseconds.
+        days += weeks*7
+        seconds += minutes*60 + hours*3600
+        microseconds += milliseconds*1000
+
+        # Get rid of all fractions, and normalize s and us.
+        # Take a deep breath <wink>.
+        if isinstance(days, float):
+            dayfrac, days = _math.modf(days)
+            daysecondsfrac, daysecondswhole = _math.modf(dayfrac * (24.*3600.))
+            assert daysecondswhole == int(daysecondswhole)  # can't overflow
+            s = int(daysecondswhole)
+            assert days == int(days)
+            d = int(days)
+        else:
+            daysecondsfrac = 0.0
+            d = days
+        assert isinstance(daysecondsfrac, float)
+        assert abs(daysecondsfrac) <= 1.0
+        assert isinstance(d, int)
+        assert abs(s) <= 24 * 3600
+        # days isn't referenced again before redefinition
+
+        if isinstance(seconds, float):
+            secondsfrac, seconds = _math.modf(seconds)
+            assert seconds == int(seconds)
+            seconds = int(seconds)
+            secondsfrac += daysecondsfrac
+            assert abs(secondsfrac) <= 2.0
+        else:
+            secondsfrac = daysecondsfrac
+        # daysecondsfrac isn't referenced again
+        assert isinstance(secondsfrac, float)
+        assert abs(secondsfrac) <= 2.0
+
+        assert isinstance(seconds, int)
+        days, seconds = divmod(seconds, 24*3600)
+        d += days
+        s += int(seconds)    # can't overflow
+        assert isinstance(s, int)
+        assert abs(s) <= 2 * 24 * 3600
+        # seconds isn't referenced again before redefinition
+
+        usdouble = secondsfrac * 1e6
+        assert abs(usdouble) < 2.1e6    # exact value not critical
+        # secondsfrac isn't referenced again
+
+        if isinstance(microseconds, float):
+            microseconds = round(microseconds + usdouble)
+            seconds, microseconds = divmod(microseconds, 1000000)
+            days, seconds = divmod(seconds, 24*3600)
+            d += days
+            s += seconds
+        else:
+            microseconds = int(microseconds)
+            seconds, microseconds = divmod(microseconds, 1000000)
+            days, seconds = divmod(seconds, 24*3600)
+            d += days
+            s += seconds
+            microseconds = round(microseconds + usdouble)
+        assert isinstance(s, int)
+        assert isinstance(microseconds, int)
+        assert abs(s) <= 3 * 24 * 3600
+        assert abs(microseconds) < 3.1e6
+
+        # Just a little bit of carrying possible for microseconds and seconds.
+        seconds, us = divmod(microseconds, 1000000)
+        s += seconds
+        days, s = divmod(s, 24*3600)
+        d += days
+
+        assert isinstance(d, int)
+        assert isinstance(s, int) and 0 <= s < 24*3600
+        assert isinstance(us, int) and 0 <= us < 1000000
+
+        if abs(d) > 999999999:
+            raise OverflowError("timedelta # of days is too large: %d" % d)
+
+        self = object.__new__(cls)
+        self._days = d
+        self._seconds = s
+        self._microseconds = us
+        self._hashcode = -1
+        return self
+
+    def __repr__(self):
+        args = []
+        if self._days:
+            args.append("days=%d" % self._days)
+        if self._seconds:
+            args.append("seconds=%d" % self._seconds)
+        if self._microseconds:
+            args.append("microseconds=%d" % self._microseconds)
+        if not args:
+            args.append('0')
+        return "%s.%s(%s)" % (self.__class__.__module__,
+                              self.__class__.__qualname__,
+                              ', '.join(args))
+
+    def __str__(self):
+        mm, ss = divmod(self._seconds, 60)
+        hh, mm = divmod(mm, 60)
+        s = "%d:%02d:%02d" % (hh, mm, ss)
+        if self._days:
+            def plural(n):
+                return n, abs(n) != 1 and "s" or ""
+            s = ("%d day%s, " % plural(self._days)) + s
+        if self._microseconds:
+            s = s + ".%06d" % self._microseconds
+        return s
+
+    def total_seconds(self):
+        """Total seconds in the duration."""
+        return ((self.days * 86400 + self.seconds) * 10**6 +
+                self.microseconds) / 10**6
+
+    # Read-only field accessors
+    @property
+    def days(self):
+        """days"""
+        return self._days
+
+    @property
+    def seconds(self):
+        """seconds"""
+        return self._seconds
+
+    @property
+    def microseconds(self):
+        """microseconds"""
+        return self._microseconds
+
+    def __add__(self, other):
+        if isinstance(other, timedelta):
+            # for CPython compatibility, we cannot use
+            # our __class__ here, but need a real timedelta
+            return timedelta(self._days + other._days,
+                             self._seconds + other._seconds,
+                             self._microseconds + other._microseconds)
+        return NotImplemented
+
+    __radd__ = __add__
+
+    def __sub__(self, other):
+        if isinstance(other, timedelta):
+            # for CPython compatibility, we cannot use
+            # our __class__ here, but need a real timedelta
+            return timedelta(self._days - other._days,
+                             self._seconds - other._seconds,
+                             self._microseconds - other._microseconds)
+        return NotImplemented
+
+    def __rsub__(self, other):
+        if isinstance(other, timedelta):
+            return -self + other
+        return NotImplemented
+
+    def __neg__(self):
+        # for CPython compatibility, we cannot use
+        # our __class__ here, but need a real timedelta
+        return timedelta(-self._days,
+                         -self._seconds,
+                         -self._microseconds)
+
+    def __pos__(self):
+        return self
+
+    def __abs__(self):
+        if self._days < 0:
+            return -self
+        else:
+            return self
+
+    def __mul__(self, other):
+        if isinstance(other, int):
+            # for CPython compatibility, we cannot use
+            # our __class__ here, but need a real timedelta
+            return timedelta(self._days * other,
+                             self._seconds * other,
+                             self._microseconds * other)
+        if isinstance(other, float):
+            usec = self._to_microseconds()
+            a, b = other.as_integer_ratio()
+            return timedelta(0, 0, _divide_and_round(usec * a, b))
+        return NotImplemented
+
+    __rmul__ = __mul__
+
+    def _to_microseconds(self):
+        return ((self._days * (24*3600) + self._seconds) * 1000000 +
+                self._microseconds)
+
+    def __floordiv__(self, other):
+        if not isinstance(other, (int, timedelta)):
+            return NotImplemented
+        usec = self._to_microseconds()
+        if isinstance(other, timedelta):
+            return usec // other._to_microseconds()
+        if isinstance(other, int):
+            return timedelta(0, 0, usec // other)
+
+    def __truediv__(self, other):
+        if not isinstance(other, (int, float, timedelta)):
+            return NotImplemented
+        usec = self._to_microseconds()
+        if isinstance(other, timedelta):
+            return usec / other._to_microseconds()
+        if isinstance(other, int):
+            return timedelta(0, 0, _divide_and_round(usec, other))
+        if isinstance(other, float):
+            a, b = other.as_integer_ratio()
+            return timedelta(0, 0, _divide_and_round(b * usec, a))
+
+    def __mod__(self, other):
+        if isinstance(other, timedelta):
+            r = self._to_microseconds() % other._to_microseconds()
+            return timedelta(0, 0, r)
+        return NotImplemented
+
+    def __divmod__(self, other):
+        if isinstance(other, timedelta):
+            q, r = divmod(self._to_microseconds(),
+                          other._to_microseconds())
+            return q, timedelta(0, 0, r)
+        return NotImplemented
+
+    # Comparisons of timedelta objects with other.
+
+    def __eq__(self, other):
+        if isinstance(other, timedelta):
+            return self._cmp(other) == 0
+        else:
+            return NotImplemented
+
+    def __le__(self, other):
+        if isinstance(other, timedelta):
+            return self._cmp(other) <= 0
+        else:
+            return NotImplemented
+
+    def __lt__(self, other):
+        if isinstance(other, timedelta):
+            return self._cmp(other) < 0
+        else:
+            return NotImplemented
+
+    def __ge__(self, other):
+        if isinstance(other, timedelta):
+            return self._cmp(other) >= 0
+        else:
+            return NotImplemented
+
+    def __gt__(self, other):
+        if isinstance(other, timedelta):
+            return self._cmp(other) > 0
+        else:
+            return NotImplemented
+
+    def _cmp(self, other):
+        assert isinstance(other, timedelta)
+        return _cmp(self._getstate(), other._getstate())
+
+    def __hash__(self):
+        if self._hashcode == -1:
+            self._hashcode = hash(self._getstate())
+        return self._hashcode
+
+    def __bool__(self):
+        return (self._days != 0 or
+                self._seconds != 0 or
+                self._microseconds != 0)
+
+    # Pickle support.
+
+    def _getstate(self):
+        return (self._days, self._seconds, self._microseconds)
+
+    def __reduce__(self):
+        return (self.__class__, self._getstate())
+
+timedelta.min = timedelta(-999999999)
+timedelta.max = timedelta(days=999999999, hours=23, minutes=59, seconds=59,
+                          microseconds=999999)
+timedelta.resolution = timedelta(microseconds=1)
+
+class date:
+    """Concrete date type.
+
+    Constructors:
+
+    __new__()
+    fromtimestamp()
+    today()
+    fromordinal()
+
+    Operators:
+
+    __repr__, __str__
+    __eq__, __le__, __lt__, __ge__, __gt__, __hash__
+    __add__, __radd__, __sub__ (add/radd only with timedelta arg)
+
+    Methods:
+
+    timetuple()
+    toordinal()
+    weekday()
+    isoweekday(), isocalendar(), isoformat()
+    ctime()
+    strftime()
+
+    Properties (readonly):
+    year, month, day
+    """
+    __slots__ = '_year', '_month', '_day', '_hashcode'
+
+    def __new__(cls, year, month=None, day=None):
+        """Constructor.
+
+        Arguments:
+
+        year, month, day (required, base 1)
+        """
+        if (month is None and
+            isinstance(year, (bytes, str)) and len(year) == 4 and
+            1 <= ord(year[2:3]) <= 12):
+            # Pickle support
+            if isinstance(year, str):
+                try:
+                    year = year.encode('latin1')
+                except UnicodeEncodeError:
+                    # More informative error message.
+                    raise ValueError(
+                        "Failed to encode latin1 string when unpickling "
+                        "a date object. "
+                        "pickle.load(data, encoding='latin1') is assumed.")
+            self = object.__new__(cls)
+            self.__setstate(year)
+            self._hashcode = -1
+            return self
+        year, month, day = _check_date_fields(year, month, day)
+        self = object.__new__(cls)
+        self._year = year
+        self._month = month
+        self._day = day
+        self._hashcode = -1
+        return self
+
+    # Additional constructors
+
+    @classmethod
+    def fromtimestamp(cls, t):
+        "Construct a date from a POSIX timestamp (like time.time())."
+        y, m, d, hh, mm, ss, weekday, jday, dst = _time.localtime(t)
+        return cls(y, m, d)
+
+    @classmethod
+    def today(cls):
+        "Construct a date from time.time()."
+        t = _time.time()
+        return cls.fromtimestamp(t)
+
+    @classmethod
+    def fromordinal(cls, n):
+        """Construct a date from a proleptic Gregorian ordinal.
+
+        January 1 of year 1 is day 1.  Only the year, month and day are
+        non-zero in the result.
+        """
+        y, m, d = _ord2ymd(n)
+        return cls(y, m, d)
+
+    @classmethod
+    def fromisoformat(cls, date_string):
+        """Construct a date from a string in ISO 8601 format."""
+        if not isinstance(date_string, str):
+            raise TypeError('fromisoformat: argument must be str')
+
+        if len(date_string) not in (7, 8, 10):
+            raise ValueError(f'Invalid isoformat string: {date_string!r}')
+
+        try:
+            return cls(*_parse_isoformat_date(date_string))
+        except Exception:
+            raise ValueError(f'Invalid isoformat string: {date_string!r}')
+
+    @classmethod
+    def fromisocalendar(cls, year, week, day):
+        """Construct a date from the ISO year, week number and weekday.
+
+        This is the inverse of the date.isocalendar() function"""
+        return cls(*_isoweek_to_gregorian(year, week, day))
+
+    # Conversions to string
+
+    def __repr__(self):
+        """Convert to formal string, for repr().
+
+        >>> dt = datetime(2010, 1, 1)
+        >>> repr(dt)
+        'datetime.datetime(2010, 1, 1, 0, 0)'
+
+        >>> dt = datetime(2010, 1, 1, tzinfo=timezone.utc)
+        >>> repr(dt)
+        'datetime.datetime(2010, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)'
+        """
+        return "%s.%s(%d, %d, %d)" % (self.__class__.__module__,
+                                      self.__class__.__qualname__,
+                                      self._year,
+                                      self._month,
+                                      self._day)
+    # XXX These shouldn't depend on time.localtime(), because that
+    # clips the usable dates to [1970 .. 2038).  At least ctime() is
+    # easily done without using strftime() -- that's better too because
+    # strftime("%c", ...) is locale specific.
+
+
+    def ctime(self):
+        "Return ctime() style string."
+        weekday = self.toordinal() % 7 or 7
+        return "%s %s %2d 00:00:00 %04d" % (
+            _DAYNAMES[weekday],
+            _MONTHNAMES[self._month],
+            self._day, self._year)
+
+    def strftime(self, format):
+        """
+        Format using strftime().
+
+        Example: "%d/%m/%Y, %H:%M:%S"
+        """
+        return _wrap_strftime(self, format, self.timetuple())
+
+    def __format__(self, fmt):
+        if not isinstance(fmt, str):
+            raise TypeError("must be str, not %s" % type(fmt).__name__)
+        if len(fmt) != 0:
+            return self.strftime(fmt)
+        return str(self)
+
+    def isoformat(self):
+        """Return the date formatted according to ISO.
+
+        This is 'YYYY-MM-DD'.
+
+        References:
+        - http://www.w3.org/TR/NOTE-datetime
+        - http://www.cl.cam.ac.uk/~mgk25/iso-time.html
+        """
+        return "%04d-%02d-%02d" % (self._year, self._month, self._day)
+
+    __str__ = isoformat
+
+    # Read-only field accessors
+    @property
+    def year(self):
+        """year (1-9999)"""
+        return self._year
+
+    @property
+    def month(self):
+        """month (1-12)"""
+        return self._month
+
+    @property
+    def day(self):
+        """day (1-31)"""
+        return self._day
+
+    # Standard conversions, __eq__, __le__, __lt__, __ge__, __gt__,
+    # __hash__ (and helpers)
+
+    def timetuple(self):
+        "Return local time tuple compatible with time.localtime()."
+        return _build_struct_time(self._year, self._month, self._day,
+                                  0, 0, 0, -1)
+
+    def toordinal(self):
+        """Return proleptic Gregorian ordinal for the year, month and day.
+
+        January 1 of year 1 is day 1.  Only the year, month and day values
+        contribute to the result.
+        """
+        return _ymd2ord(self._year, self._month, self._day)
+
+    def replace(self, year=None, month=None, day=None):
+        """Return a new date with new values for the specified fields."""
+        if year is None:
+            year = self._year
+        if month is None:
+            month = self._month
+        if day is None:
+            day = self._day
+        return type(self)(year, month, day)
+
+    # Comparisons of date objects with other.
+
+    def __eq__(self, other):
+        if isinstance(other, date):
+            return self._cmp(other) == 0
+        return NotImplemented
+
+    def __le__(self, other):
+        if isinstance(other, date):
+            return self._cmp(other) <= 0
+        return NotImplemented
+
+    def __lt__(self, other):
+        if isinstance(other, date):
+            return self._cmp(other) < 0
+        return NotImplemented
+
+    def __ge__(self, other):
+        if isinstance(other, date):
+            return self._cmp(other) >= 0
+        return NotImplemented
+
+    def __gt__(self, other):
+        if isinstance(other, date):
+            return self._cmp(other) > 0
+        return NotImplemented
+
+    def _cmp(self, other):
+        assert isinstance(other, date)
+        y, m, d = self._year, self._month, self._day
+        y2, m2, d2 = other._year, other._month, other._day
+        return _cmp((y, m, d), (y2, m2, d2))
+
+    def __hash__(self):
+        "Hash."
+        if self._hashcode == -1:
+            self._hashcode = hash(self._getstate())
+        return self._hashcode
+
+    # Computations
+
+    def __add__(self, other):
+        "Add a date to a timedelta."
+        if isinstance(other, timedelta):
+            o = self.toordinal() + other.days
+            if 0 < o <= _MAXORDINAL:
+                return type(self).fromordinal(o)
+            raise OverflowError("result out of range")
+        return NotImplemented
+
+    __radd__ = __add__
+
+    def __sub__(self, other):
+        """Subtract two dates, or a date and a timedelta."""
+        if isinstance(other, timedelta):
+            return self + timedelta(-other.days)
+        if isinstance(other, date):
+            days1 = self.toordinal()
+            days2 = other.toordinal()
+            return timedelta(days1 - days2)
+        return NotImplemented
+
+    def weekday(self):
+        "Return day of the week, where Monday == 0 ... Sunday == 6."
+        return (self.toordinal() + 6) % 7
+
+    # Day-of-the-week and week-of-the-year, according to ISO
+
+    def isoweekday(self):
+        "Return day of the week, where Monday == 1 ... Sunday == 7."
+        # 1-Jan-0001 is a Monday
+        return self.toordinal() % 7 or 7
+
+    def isocalendar(self):
+        """Return a named tuple containing ISO year, week number, and weekday.
+
+        The first ISO week of the year is the (Mon-Sun) week
+        containing the year's first Thursday; everything else derives
+        from that.
+
+        The first week is 1; Monday is 1 ... Sunday is 7.
+
+        ISO calendar algorithm taken from
+        http://www.phys.uu.nl/~vgent/calendar/isocalendar.htm
+        (used with permission)
+        """
+        year = self._year
+        week1monday = _isoweek1monday(year)
+        today = _ymd2ord(self._year, self._month, self._day)
+        # Internally, week and day have origin 0
+        week, day = divmod(today - week1monday, 7)
+        if week < 0:
+            year -= 1
+            week1monday = _isoweek1monday(year)
+            week, day = divmod(today - week1monday, 7)
+        elif week >= 52:
+            if today >= _isoweek1monday(year+1):
+                year += 1
+                week = 0
+        return _IsoCalendarDate(year, week+1, day+1)
+
+    # Pickle support.
+
+    def _getstate(self):
+        yhi, ylo = divmod(self._year, 256)
+        return bytes([yhi, ylo, self._month, self._day]),
+
+    def __setstate(self, string):
+        yhi, ylo, self._month, self._day = string
+        self._year = yhi * 256 + ylo
+
+    def __reduce__(self):
+        return (self.__class__, self._getstate())
+
+_date_class = date  # so functions w/ args named "date" can get at the class
+
+date.min = date(1, 1, 1)
+date.max = date(9999, 12, 31)
+date.resolution = timedelta(days=1)
+
+
+class tzinfo:
+    """Abstract base class for time zone info classes.
+
+    Subclasses must override the name(), utcoffset() and dst() methods.
+    """
+    __slots__ = ()
+
+    def tzname(self, dt):
+        "datetime -> string name of time zone."
+        raise NotImplementedError("tzinfo subclass must override tzname()")
+
+    def utcoffset(self, dt):
+        "datetime -> timedelta, positive for east of UTC, negative for west of UTC"
+        raise NotImplementedError("tzinfo subclass must override utcoffset()")
+
+    def dst(self, dt):
+        """datetime -> DST offset as timedelta, positive for east of UTC.
+
+        Return 0 if DST not in effect.  utcoffset() must include the DST
+        offset.
+        """
+        raise NotImplementedError("tzinfo subclass must override dst()")
+
+    def fromutc(self, dt):
+        "datetime in UTC -> datetime in local time."
+
+        if not isinstance(dt, datetime):
+            raise TypeError("fromutc() requires a datetime argument")
+        if dt.tzinfo is not self:
+            raise ValueError("dt.tzinfo is not self")
+
+        dtoff = dt.utcoffset()
+        if dtoff is None:
+            raise ValueError("fromutc() requires a non-None utcoffset() "
+                             "result")
+
+        # See the long comment block at the end of this file for an
+        # explanation of this algorithm.
+        dtdst = dt.dst()
+        if dtdst is None:
+            raise ValueError("fromutc() requires a non-None dst() result")
+        delta = dtoff - dtdst
+        if delta:
+            dt += delta
+            dtdst = dt.dst()
+            if dtdst is None:
+                raise ValueError("fromutc(): dt.dst gave inconsistent "
+                                 "results; cannot convert")
+        return dt + dtdst
+
+    # Pickle support.
+
+    def __reduce__(self):
+        getinitargs = getattr(self, "__getinitargs__", None)
+        if getinitargs:
+            args = getinitargs()
+        else:
+            args = ()
+        return (self.__class__, args, self.__getstate__())
+
+
+class IsoCalendarDate(tuple):
+
+    def __new__(cls, year, week, weekday, /):
+        return super().__new__(cls, (year, week, weekday))
+
+    @property
+    def year(self):
+        return self[0]
+
+    @property
+    def week(self):
+        return self[1]
+
+    @property
+    def weekday(self):
+        return self[2]
+
+    def __reduce__(self):
+        # This code is intended to pickle the object without making the
+        # class public. See https://bugs.python.org/msg352381
+        return (tuple, (tuple(self),))
+
+    def __repr__(self):
+        return (f'{self.__class__.__name__}'
+                f'(year={self[0]}, week={self[1]}, weekday={self[2]})')
+
+
+_IsoCalendarDate = IsoCalendarDate
+del IsoCalendarDate
+_tzinfo_class = tzinfo
+
+class time:
+    """Time with time zone.
+
+    Constructors:
+
+    __new__()
+
+    Operators:
+
+    __repr__, __str__
+    __eq__, __le__, __lt__, __ge__, __gt__, __hash__
+
+    Methods:
+
+    strftime()
+    isoformat()
+    utcoffset()
+    tzname()
+    dst()
+
+    Properties (readonly):
+    hour, minute, second, microsecond, tzinfo, fold
+    """
+    __slots__ = '_hour', '_minute', '_second', '_microsecond', '_tzinfo', '_hashcode', '_fold'
+
+    def __new__(cls, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0):
+        """Constructor.
+
+        Arguments:
+
+        hour, minute (required)
+        second, microsecond (default to zero)
+        tzinfo (default to None)
+        fold (keyword only, default to zero)
+        """
+        if (isinstance(hour, (bytes, str)) and len(hour) == 6 and
+            ord(hour[0:1])&0x7F < 24):
+            # Pickle support
+            if isinstance(hour, str):
+                try:
+                    hour = hour.encode('latin1')
+                except UnicodeEncodeError:
+                    # More informative error message.
+                    raise ValueError(
+                        "Failed to encode latin1 string when unpickling "
+                        "a time object. "
+                        "pickle.load(data, encoding='latin1') is assumed.")
+            self = object.__new__(cls)
+            self.__setstate(hour, minute or None)
+            self._hashcode = -1
+            return self
+        hour, minute, second, microsecond, fold = _check_time_fields(
+            hour, minute, second, microsecond, fold)
+        _check_tzinfo_arg(tzinfo)
+        self = object.__new__(cls)
+        self._hour = hour
+        self._minute = minute
+        self._second = second
+        self._microsecond = microsecond
+        self._tzinfo = tzinfo
+        self._hashcode = -1
+        self._fold = fold
+        return self
+
+    # Read-only field accessors
+    @property
+    def hour(self):
+        """hour (0-23)"""
+        return self._hour
+
+    @property
+    def minute(self):
+        """minute (0-59)"""
+        return self._minute
+
+    @property
+    def second(self):
+        """second (0-59)"""
+        return self._second
+
+    @property
+    def microsecond(self):
+        """microsecond (0-999999)"""
+        return self._microsecond
+
+    @property
+    def tzinfo(self):
+        """timezone info object"""
+        return self._tzinfo
+
+    @property
+    def fold(self):
+        return self._fold
+
+    # Standard conversions, __hash__ (and helpers)
+
+    # Comparisons of time objects with other.
+
+    def __eq__(self, other):
+        if isinstance(other, time):
+            return self._cmp(other, allow_mixed=True) == 0
+        else:
+            return NotImplemented
+
+    def __le__(self, other):
+        if isinstance(other, time):
+            return self._cmp(other) <= 0
+        else:
+            return NotImplemented
+
+    def __lt__(self, other):
+        if isinstance(other, time):
+            return self._cmp(other) < 0
+        else:
+            return NotImplemented
+
+    def __ge__(self, other):
+        if isinstance(other, time):
+            return self._cmp(other) >= 0
+        else:
+            return NotImplemented
+
+    def __gt__(self, other):
+        if isinstance(other, time):
+            return self._cmp(other) > 0
+        else:
+            return NotImplemented
+
+    def _cmp(self, other, allow_mixed=False):
+        assert isinstance(other, time)
+        mytz = self._tzinfo
+        ottz = other._tzinfo
+        myoff = otoff = None
+
+        if mytz is ottz:
+            base_compare = True
+        else:
+            myoff = self.utcoffset()
+            otoff = other.utcoffset()
+            base_compare = myoff == otoff
+
+        if base_compare:
+            return _cmp((self._hour, self._minute, self._second,
+                         self._microsecond),
+                        (other._hour, other._minute, other._second,
+                         other._microsecond))
+        if myoff is None or otoff is None:
+            if allow_mixed:
+                return 2 # arbitrary non-zero value
+            else:
+                raise TypeError("cannot compare naive and aware times")
+        myhhmm = self._hour * 60 + self._minute - myoff//timedelta(minutes=1)
+        othhmm = other._hour * 60 + other._minute - otoff//timedelta(minutes=1)
+        return _cmp((myhhmm, self._second, self._microsecond),
+                    (othhmm, other._second, other._microsecond))
+
+    def __hash__(self):
+        """Hash."""
+        if self._hashcode == -1:
+            if self.fold:
+                t = self.replace(fold=0)
+            else:
+                t = self
+            tzoff = t.utcoffset()
+            if not tzoff:  # zero or None
+                self._hashcode = hash(t._getstate()[0])
+            else:
+                h, m = divmod(timedelta(hours=self.hour, minutes=self.minute) - tzoff,
+                              timedelta(hours=1))
+                assert not m % timedelta(minutes=1), "whole minute"
+                m //= timedelta(minutes=1)
+                if 0 <= h < 24:
+                    self._hashcode = hash(time(h, m, self.second, self.microsecond))
+                else:
+                    self._hashcode = hash((h, m, self.second, self.microsecond))
+        return self._hashcode
+
+    # Conversion to string
+
+    def _tzstr(self):
+        """Return formatted timezone offset (+xx:xx) or an empty string."""
+        off = self.utcoffset()
+        return _format_offset(off)
+
+    def __repr__(self):
+        """Convert to formal string, for repr()."""
+        if self._microsecond != 0:
+            s = ", %d, %d" % (self._second, self._microsecond)
+        elif self._second != 0:
+            s = ", %d" % self._second
+        else:
+            s = ""
+        s= "%s.%s(%d, %d%s)" % (self.__class__.__module__,
+                                self.__class__.__qualname__,
+                                self._hour, self._minute, s)
+        if self._tzinfo is not None:
+            assert s[-1:] == ")"
+            s = s[:-1] + ", tzinfo=%r" % self._tzinfo + ")"
+        if self._fold:
+            assert s[-1:] == ")"
+            s = s[:-1] + ", fold=1)"
+        return s
+
+    def isoformat(self, timespec='auto'):
+        """Return the time formatted according to ISO.
+
+        The full format is 'HH:MM:SS.mmmmmm+zz:zz'. By default, the fractional
+        part is omitted if self.microsecond == 0.
+
+        The optional argument timespec specifies the number of additional
+        terms of the time to include. Valid options are 'auto', 'hours',
+        'minutes', 'seconds', 'milliseconds' and 'microseconds'.
+        """
+        s = _format_time(self._hour, self._minute, self._second,
+                          self._microsecond, timespec)
+        tz = self._tzstr()
+        if tz:
+            s += tz
+        return s
+
+    __str__ = isoformat
+
+    @classmethod
+    def fromisoformat(cls, time_string):
+        """Construct a time from a string in one of the ISO 8601 formats."""
+        if not isinstance(time_string, str):
+            raise TypeError('fromisoformat: argument must be str')
+
+        # The spec actually requires that time-only ISO 8601 strings start with
+        # T, but the extended format allows this to be omitted as long as there
+        # is no ambiguity with date strings.
+        time_string = time_string.removeprefix('T')
+
+        try:
+            return cls(*_parse_isoformat_time(time_string))
+        except Exception:
+            raise ValueError(f'Invalid isoformat string: {time_string!r}')
+
+    def strftime(self, format):
+        """Format using strftime().  The date part of the timestamp passed
+        to underlying strftime should not be used.
+        """
+        # The year must be >= 1000 else Python's strftime implementation
+        # can raise a bogus exception.
+        timetuple = (1900, 1, 1,
+                     self._hour, self._minute, self._second,
+                     0, 1, -1)
+        return _wrap_strftime(self, format, timetuple)
+
+    def __format__(self, fmt):
+        if not isinstance(fmt, str):
+            raise TypeError("must be str, not %s" % type(fmt).__name__)
+        if len(fmt) != 0:
+            return self.strftime(fmt)
+        return str(self)
+
+    # Timezone functions
+
+    def utcoffset(self):
+        """Return the timezone offset as timedelta, positive east of UTC
+         (negative west of UTC)."""
+        if self._tzinfo is None:
+            return None
+        offset = self._tzinfo.utcoffset(None)
+        _check_utc_offset("utcoffset", offset)
+        return offset
+
+    def tzname(self):
+        """Return the timezone name.
+
+        Note that the name is 100% informational -- there's no requirement that
+        it mean anything in particular. For example, "GMT", "UTC", "-500",
+        "-5:00", "EDT", "US/Eastern", "America/New York" are all valid replies.
+        """
+        if self._tzinfo is None:
+            return None
+        name = self._tzinfo.tzname(None)
+        _check_tzname(name)
+        return name
+
+    def dst(self):
+        """Return 0 if DST is not in effect, or the DST offset (as timedelta
+        positive eastward) if DST is in effect.
+
+        This is purely informational; the DST offset has already been added to
+        the UTC offset returned by utcoffset() if applicable, so there's no
+        need to consult dst() unless you're interested in displaying the DST
+        info.
+        """
+        if self._tzinfo is None:
+            return None
+        offset = self._tzinfo.dst(None)
+        _check_utc_offset("dst", offset)
+        return offset
+
+    def replace(self, hour=None, minute=None, second=None, microsecond=None,
+                tzinfo=True, *, fold=None):
+        """Return a new time with new values for the specified fields."""
+        if hour is None:
+            hour = self.hour
+        if minute is None:
+            minute = self.minute
+        if second is None:
+            second = self.second
+        if microsecond is None:
+            microsecond = self.microsecond
+        if tzinfo is True:
+            tzinfo = self.tzinfo
+        if fold is None:
+            fold = self._fold
+        return type(self)(hour, minute, second, microsecond, tzinfo, fold=fold)
+
+    # Pickle support.
+
+    def _getstate(self, protocol=3):
+        us2, us3 = divmod(self._microsecond, 256)
+        us1, us2 = divmod(us2, 256)
+        h = self._hour
+        if self._fold and protocol > 3:
+            h += 128
+        basestate = bytes([h, self._minute, self._second,
+                           us1, us2, us3])
+        if self._tzinfo is None:
+            return (basestate,)
+        else:
+            return (basestate, self._tzinfo)
+
+    def __setstate(self, string, tzinfo):
+        if tzinfo is not None and not isinstance(tzinfo, _tzinfo_class):
+            raise TypeError("bad tzinfo state arg")
+        h, self._minute, self._second, us1, us2, us3 = string
+        if h > 127:
+            self._fold = 1
+            self._hour = h - 128
+        else:
+            self._fold = 0
+            self._hour = h
+        self._microsecond = (((us1 << 8) | us2) << 8) | us3
+        self._tzinfo = tzinfo
+
+    def __reduce_ex__(self, protocol):
+        return (self.__class__, self._getstate(protocol))
+
+    def __reduce__(self):
+        return self.__reduce_ex__(2)
+
+_time_class = time  # so functions w/ args named "time" can get at the class
+
+time.min = time(0, 0, 0)
+time.max = time(23, 59, 59, 999999)
+time.resolution = timedelta(microseconds=1)
+
+
+class datetime(date):
+    """datetime(year, month, day[, hour[, minute[, second[, microsecond[,tzinfo]]]]])
+
+    The year, month and day arguments are required. tzinfo may be None, or an
+    instance of a tzinfo subclass. The remaining arguments may be ints.
+    """
+    __slots__ = date.__slots__ + time.__slots__
+
+    def __new__(cls, year, month=None, day=None, hour=0, minute=0, second=0,
+                microsecond=0, tzinfo=None, *, fold=0):
+        if (isinstance(year, (bytes, str)) and len(year) == 10 and
+            1 <= ord(year[2:3])&0x7F <= 12):
+            # Pickle support
+            if isinstance(year, str):
+                try:
+                    year = bytes(year, 'latin1')
+                except UnicodeEncodeError:
+                    # More informative error message.
+                    raise ValueError(
+                        "Failed to encode latin1 string when unpickling "
+                        "a datetime object. "
+                        "pickle.load(data, encoding='latin1') is assumed.")
+            self = object.__new__(cls)
+            self.__setstate(year, month)
+            self._hashcode = -1
+            return self
+        year, month, day = _check_date_fields(year, month, day)
+        hour, minute, second, microsecond, fold = _check_time_fields(
+            hour, minute, second, microsecond, fold)
+        _check_tzinfo_arg(tzinfo)
+        self = object.__new__(cls)
+        self._year = year
+        self._month = month
+        self._day = day
+        self._hour = hour
+        self._minute = minute
+        self._second = second
+        self._microsecond = microsecond
+        self._tzinfo = tzinfo
+        self._hashcode = -1
+        self._fold = fold
+        return self
+
+    # Read-only field accessors
+    @property
+    def hour(self):
+        """hour (0-23)"""
+        return self._hour
+
+    @property
+    def minute(self):
+        """minute (0-59)"""
+        return self._minute
+
+    @property
+    def second(self):
+        """second (0-59)"""
+        return self._second
+
+    @property
+    def microsecond(self):
+        """microsecond (0-999999)"""
+        return self._microsecond
+
+    @property
+    def tzinfo(self):
+        """timezone info object"""
+        return self._tzinfo
+
+    @property
+    def fold(self):
+        return self._fold
+
+    @classmethod
+    def _fromtimestamp(cls, t, utc, tz):
+        """Construct a datetime from a POSIX timestamp (like time.time()).
+
+        A timezone info object may be passed in as well.
+        """
+        frac, t = _math.modf(t)
+        us = round(frac * 1e6)
+        if us >= 1000000:
+            t += 1
+            us -= 1000000
+        elif us < 0:
+            t -= 1
+            us += 1000000
+
+        converter = _time.gmtime if utc else _time.localtime
+        y, m, d, hh, mm, ss, weekday, jday, dst = converter(t)
+        ss = min(ss, 59)    # clamp out leap seconds if the platform has them
+        result = cls(y, m, d, hh, mm, ss, us, tz)
+        if tz is None and not utc:
+            # As of version 2015f max fold in IANA database is
+            # 23 hours at 1969-09-30 13:00:00 in Kwajalein.
+            # Let's probe 24 hours in the past to detect a transition:
+            max_fold_seconds = 24 * 3600
+
+            # On Windows localtime_s throws an OSError for negative values,
+            # thus we can't perform fold detection for values of time less
+            # than the max time fold. See comments in _datetimemodule's
+            # version of this method for more details.
+            if t < max_fold_seconds and sys.platform.startswith("win"):
+                return result
+
+            y, m, d, hh, mm, ss = converter(t - max_fold_seconds)[:6]
+            probe1 = cls(y, m, d, hh, mm, ss, us, tz)
+            trans = result - probe1 - timedelta(0, max_fold_seconds)
+            if trans.days < 0:
+                y, m, d, hh, mm, ss = converter(t + trans // timedelta(0, 1))[:6]
+                probe2 = cls(y, m, d, hh, mm, ss, us, tz)
+                if probe2 == result:
+                    result._fold = 1
+        elif tz is not None:
+            result = tz.fromutc(result)
+        return result
+
+    @classmethod
+    def fromtimestamp(cls, timestamp, tz=None):
+        """Construct a datetime from a POSIX timestamp (like time.time()).
+
+        A timezone info object may be passed in as well.
+        """
+        _check_tzinfo_arg(tz)
+
+        return cls._fromtimestamp(timestamp, tz is not None, tz)
+
+    @classmethod
+    def utcfromtimestamp(cls, t):
+        """Construct a naive UTC datetime from a POSIX timestamp."""
+        import warnings
+        warnings.warn("datetime.utcfromtimestamp() is deprecated and scheduled "
+                      "for removal in a future version. Use timezone-aware "
+                      "objects to represent datetimes in UTC: "
+                      "datetime.fromtimestamp(t, datetime.UTC).",
+                      DeprecationWarning,
+                      stacklevel=2)
+        return cls._fromtimestamp(t, True, None)
+
+    @classmethod
+    def now(cls, tz=None):
+        "Construct a datetime from time.time() and optional time zone info."
+        t = _time.time()
+        return cls.fromtimestamp(t, tz)
+
+    @classmethod
+    def utcnow(cls):
+        "Construct a UTC datetime from time.time()."
+        import warnings
+        warnings.warn("datetime.utcnow() is deprecated and scheduled for "
+                      "removal in a future version. Instead, Use timezone-aware "
+                      "objects to represent datetimes in UTC: "
+                      "datetime.now(datetime.UTC).",
+                      DeprecationWarning,
+                      stacklevel=2)
+        t = _time.time()
+        return cls._fromtimestamp(t, True, None)
+
+    @classmethod
+    def combine(cls, date, time, tzinfo=True):
+        "Construct a datetime from a given date and a given time."
+        if not isinstance(date, _date_class):
+            raise TypeError("date argument must be a date instance")
+        if not isinstance(time, _time_class):
+            raise TypeError("time argument must be a time instance")
+        if tzinfo is True:
+            tzinfo = time.tzinfo
+        return cls(date.year, date.month, date.day,
+                   time.hour, time.minute, time.second, time.microsecond,
+                   tzinfo, fold=time.fold)
+
+    @classmethod
+    def fromisoformat(cls, date_string):
+        """Construct a datetime from a string in one of the ISO 8601 formats."""
+        if not isinstance(date_string, str):
+            raise TypeError('fromisoformat: argument must be str')
+
+        if len(date_string) < 7:
+            raise ValueError(f'Invalid isoformat string: {date_string!r}')
+
+        # Split this at the separator
+        try:
+            separator_location = _find_isoformat_datetime_separator(date_string)
+            dstr = date_string[0:separator_location]
+            tstr = date_string[(separator_location+1):]
+
+            date_components = _parse_isoformat_date(dstr)
+        except ValueError:
+            raise ValueError(
+                f'Invalid isoformat string: {date_string!r}') from None
+
+        if tstr:
+            try:
+                time_components = _parse_isoformat_time(tstr)
+            except ValueError:
+                raise ValueError(
+                    f'Invalid isoformat string: {date_string!r}') from None
+        else:
+            time_components = [0, 0, 0, 0, None]
+
+        return cls(*(date_components + time_components))
+
+    def timetuple(self):
+        "Return local time tuple compatible with time.localtime()."
+        dst = self.dst()
+        if dst is None:
+            dst = -1
+        elif dst:
+            dst = 1
+        else:
+            dst = 0
+        return _build_struct_time(self.year, self.month, self.day,
+                                  self.hour, self.minute, self.second,
+                                  dst)
+
+    def _mktime(self):
+        """Return integer POSIX timestamp."""
+        epoch = datetime(1970, 1, 1)
+        max_fold_seconds = 24 * 3600
+        t = (self - epoch) // timedelta(0, 1)
+        def local(u):
+            y, m, d, hh, mm, ss = _time.localtime(u)[:6]
+            return (datetime(y, m, d, hh, mm, ss) - epoch) // timedelta(0, 1)
+
+        # Our goal is to solve t = local(u) for u.
+        a = local(t) - t
+        u1 = t - a
+        t1 = local(u1)
+        if t1 == t:
+            # We found one solution, but it may not be the one we need.
+            # Look for an earlier solution (if `fold` is 0), or a
+            # later one (if `fold` is 1).
+            u2 = u1 + (-max_fold_seconds, max_fold_seconds)[self.fold]
+            b = local(u2) - u2
+            if a == b:
+                return u1
+        else:
+            b = t1 - u1
+            assert a != b
+        u2 = t - b
+        t2 = local(u2)
+        if t2 == t:
+            return u2
+        if t1 == t:
+            return u1
+        # We have found both offsets a and b, but neither t - a nor t - b is
+        # a solution.  This means t is in the gap.
+        return (max, min)[self.fold](u1, u2)
+
+
+    def timestamp(self):
+        "Return POSIX timestamp as float"
+        if self._tzinfo is None:
+            s = self._mktime()
+            return s + self.microsecond / 1e6
+        else:
+            return (self - _EPOCH).total_seconds()
+
+    def utctimetuple(self):
+        "Return UTC time tuple compatible with time.gmtime()."
+        offset = self.utcoffset()
+        if offset:
+            self -= offset
+        y, m, d = self.year, self.month, self.day
+        hh, mm, ss = self.hour, self.minute, self.second
+        return _build_struct_time(y, m, d, hh, mm, ss, 0)
+
+    def date(self):
+        "Return the date part."
+        return date(self._year, self._month, self._day)
+
+    def time(self):
+        "Return the time part, with tzinfo None."
+        return time(self.hour, self.minute, self.second, self.microsecond, fold=self.fold)
+
+    def timetz(self):
+        "Return the time part, with same tzinfo."
+        return time(self.hour, self.minute, self.second, self.microsecond,
+                    self._tzinfo, fold=self.fold)
+
+    def replace(self, year=None, month=None, day=None, hour=None,
+                minute=None, second=None, microsecond=None, tzinfo=True,
+                *, fold=None):
+        """Return a new datetime with new values for the specified fields."""
+        if year is None:
+            year = self.year
+        if month is None:
+            month = self.month
+        if day is None:
+            day = self.day
+        if hour is None:
+            hour = self.hour
+        if minute is None:
+            minute = self.minute
+        if second is None:
+            second = self.second
+        if microsecond is None:
+            microsecond = self.microsecond
+        if tzinfo is True:
+            tzinfo = self.tzinfo
+        if fold is None:
+            fold = self.fold
+        return type(self)(year, month, day, hour, minute, second,
+                          microsecond, tzinfo, fold=fold)
+
+    def _local_timezone(self):
+        if self.tzinfo is None:
+            ts = self._mktime()
+            # Detect gap
+            ts2 = self.replace(fold=1-self.fold)._mktime()
+            if ts2 != ts: # This happens in a gap or a fold
+                if (ts2 > ts) == self.fold:
+                    ts = ts2
+        else:
+            ts = (self - _EPOCH) // timedelta(seconds=1)
+        localtm = _time.localtime(ts)
+        local = datetime(*localtm[:6])
+        # Extract TZ data
+        gmtoff = localtm.tm_gmtoff
+        zone = localtm.tm_zone
+        return timezone(timedelta(seconds=gmtoff), zone)
+
+    def astimezone(self, tz=None):
+        if tz is None:
+            tz = self._local_timezone()
+        elif not isinstance(tz, tzinfo):
+            raise TypeError("tz argument must be an instance of tzinfo")
+
+        mytz = self.tzinfo
+        if mytz is None:
+            mytz = self._local_timezone()
+            myoffset = mytz.utcoffset(self)
+        else:
+            myoffset = mytz.utcoffset(self)
+            if myoffset is None:
+                mytz = self.replace(tzinfo=None)._local_timezone()
+                myoffset = mytz.utcoffset(self)
+
+        if tz is mytz:
+            return self
+
+        # Convert self to UTC, and attach the new time zone object.
+        utc = (self - myoffset).replace(tzinfo=tz)
+
+        # Convert from UTC to tz's local time.
+        return tz.fromutc(utc)
+
+    # Ways to produce a string.
+
+    def ctime(self):
+        "Return ctime() style string."
+        weekday = self.toordinal() % 7 or 7
+        return "%s %s %2d %02d:%02d:%02d %04d" % (
+            _DAYNAMES[weekday],
+            _MONTHNAMES[self._month],
+            self._day,
+            self._hour, self._minute, self._second,
+            self._year)
+
+    def isoformat(self, sep='T', timespec='auto'):
+        """Return the time formatted according to ISO.
+
+        The full format looks like 'YYYY-MM-DD HH:MM:SS.mmmmmm'.
+        By default, the fractional part is omitted if self.microsecond == 0.
+
+        If self.tzinfo is not None, the UTC offset is also attached, giving
+        giving a full format of 'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM'.
+
+        Optional argument sep specifies the separator between date and
+        time, default 'T'.
+
+        The optional argument timespec specifies the number of additional
+        terms of the time to include. Valid options are 'auto', 'hours',
+        'minutes', 'seconds', 'milliseconds' and 'microseconds'.
+        """
+        s = ("%04d-%02d-%02d%c" % (self._year, self._month, self._day, sep) +
+             _format_time(self._hour, self._minute, self._second,
+                          self._microsecond, timespec))
+
+        off = self.utcoffset()
+        tz = _format_offset(off)
+        if tz:
+            s += tz
+
+        return s
+
+    def __repr__(self):
+        """Convert to formal string, for repr()."""
+        L = [self._year, self._month, self._day,  # These are never zero
+             self._hour, self._minute, self._second, self._microsecond]
+        if L[-1] == 0:
+            del L[-1]
+        if L[-1] == 0:
+            del L[-1]
+        s = "%s.%s(%s)" % (self.__class__.__module__,
+                           self.__class__.__qualname__,
+                           ", ".join(map(str, L)))
+        if self._tzinfo is not None:
+            assert s[-1:] == ")"
+            s = s[:-1] + ", tzinfo=%r" % self._tzinfo + ")"
+        if self._fold:
+            assert s[-1:] == ")"
+            s = s[:-1] + ", fold=1)"
+        return s
+
+    def __str__(self):
+        "Convert to string, for str()."
+        return self.isoformat(sep=' ')
+
+    @classmethod
+    def strptime(cls, date_string, format):
+        'string, format -> new datetime parsed from a string (like time.strptime()).'
+        import _strptime
+        return _strptime._strptime_datetime(cls, date_string, format)
+
+    def utcoffset(self):
+        """Return the timezone offset as timedelta positive east of UTC (negative west of
+        UTC)."""
+        if self._tzinfo is None:
+            return None
+        offset = self._tzinfo.utcoffset(self)
+        _check_utc_offset("utcoffset", offset)
+        return offset
+
+    def tzname(self):
+        """Return the timezone name.
+
+        Note that the name is 100% informational -- there's no requirement that
+        it mean anything in particular. For example, "GMT", "UTC", "-500",
+        "-5:00", "EDT", "US/Eastern", "America/New York" are all valid replies.
+        """
+        if self._tzinfo is None:
+            return None
+        name = self._tzinfo.tzname(self)
+        _check_tzname(name)
+        return name
+
+    def dst(self):
+        """Return 0 if DST is not in effect, or the DST offset (as timedelta
+        positive eastward) if DST is in effect.
+
+        This is purely informational; the DST offset has already been added to
+        the UTC offset returned by utcoffset() if applicable, so there's no
+        need to consult dst() unless you're interested in displaying the DST
+        info.
+        """
+        if self._tzinfo is None:
+            return None
+        offset = self._tzinfo.dst(self)
+        _check_utc_offset("dst", offset)
+        return offset
+
+    # Comparisons of datetime objects with other.
+
+    def __eq__(self, other):
+        if isinstance(other, datetime):
+            return self._cmp(other, allow_mixed=True) == 0
+        elif not isinstance(other, date):
+            return NotImplemented
+        else:
+            return False
+
+    def __le__(self, other):
+        if isinstance(other, datetime):
+            return self._cmp(other) <= 0
+        elif not isinstance(other, date):
+            return NotImplemented
+        else:
+            _cmperror(self, other)
+
+    def __lt__(self, other):
+        if isinstance(other, datetime):
+            return self._cmp(other) < 0
+        elif not isinstance(other, date):
+            return NotImplemented
+        else:
+            _cmperror(self, other)
+
+    def __ge__(self, other):
+        if isinstance(other, datetime):
+            return self._cmp(other) >= 0
+        elif not isinstance(other, date):
+            return NotImplemented
+        else:
+            _cmperror(self, other)
+
+    def __gt__(self, other):
+        if isinstance(other, datetime):
+            return self._cmp(other) > 0
+        elif not isinstance(other, date):
+            return NotImplemented
+        else:
+            _cmperror(self, other)
+
+    def _cmp(self, other, allow_mixed=False):
+        assert isinstance(other, datetime)
+        mytz = self._tzinfo
+        ottz = other._tzinfo
+        myoff = otoff = None
+
+        if mytz is ottz:
+            base_compare = True
+        else:
+            myoff = self.utcoffset()
+            otoff = other.utcoffset()
+            # Assume that allow_mixed means that we are called from __eq__
+            if allow_mixed:
+                if myoff != self.replace(fold=not self.fold).utcoffset():
+                    return 2
+                if otoff != other.replace(fold=not other.fold).utcoffset():
+                    return 2
+            base_compare = myoff == otoff
+
+        if base_compare:
+            return _cmp((self._year, self._month, self._day,
+                         self._hour, self._minute, self._second,
+                         self._microsecond),
+                        (other._year, other._month, other._day,
+                         other._hour, other._minute, other._second,
+                         other._microsecond))
+        if myoff is None or otoff is None:
+            if allow_mixed:
+                return 2 # arbitrary non-zero value
+            else:
+                raise TypeError("cannot compare naive and aware datetimes")
+        # XXX What follows could be done more efficiently...
+        diff = self - other     # this will take offsets into account
+        if diff.days < 0:
+            return -1
+        return diff and 1 or 0
+
+    def __add__(self, other):
+        "Add a datetime and a timedelta."
+        if not isinstance(other, timedelta):
+            return NotImplemented
+        delta = timedelta(self.toordinal(),
+                          hours=self._hour,
+                          minutes=self._minute,
+                          seconds=self._second,
+                          microseconds=self._microsecond)
+        delta += other
+        hour, rem = divmod(delta.seconds, 3600)
+        minute, second = divmod(rem, 60)
+        if 0 < delta.days <= _MAXORDINAL:
+            return type(self).combine(date.fromordinal(delta.days),
+                                      time(hour, minute, second,
+                                           delta.microseconds,
+                                           tzinfo=self._tzinfo))
+        raise OverflowError("result out of range")
+
+    __radd__ = __add__
+
+    def __sub__(self, other):
+        "Subtract two datetimes, or a datetime and a timedelta."
+        if not isinstance(other, datetime):
+            if isinstance(other, timedelta):
+                return self + -other
+            return NotImplemented
+
+        days1 = self.toordinal()
+        days2 = other.toordinal()
+        secs1 = self._second + self._minute * 60 + self._hour * 3600
+        secs2 = other._second + other._minute * 60 + other._hour * 3600
+        base = timedelta(days1 - days2,
+                         secs1 - secs2,
+                         self._microsecond - other._microsecond)
+        if self._tzinfo is other._tzinfo:
+            return base
+        myoff = self.utcoffset()
+        otoff = other.utcoffset()
+        if myoff == otoff:
+            return base
+        if myoff is None or otoff is None:
+            raise TypeError("cannot mix naive and timezone-aware time")
+        return base + otoff - myoff
+
+    def __hash__(self):
+        if self._hashcode == -1:
+            if self.fold:
+                t = self.replace(fold=0)
+            else:
+                t = self
+            tzoff = t.utcoffset()
+            if tzoff is None:
+                self._hashcode = hash(t._getstate()[0])
+            else:
+                days = _ymd2ord(self.year, self.month, self.day)
+                seconds = self.hour * 3600 + self.minute * 60 + self.second
+                self._hashcode = hash(timedelta(days, seconds, self.microsecond) - tzoff)
+        return self._hashcode
+
+    # Pickle support.
+
+    def _getstate(self, protocol=3):
+        yhi, ylo = divmod(self._year, 256)
+        us2, us3 = divmod(self._microsecond, 256)
+        us1, us2 = divmod(us2, 256)
+        m = self._month
+        if self._fold and protocol > 3:
+            m += 128
+        basestate = bytes([yhi, ylo, m, self._day,
+                           self._hour, self._minute, self._second,
+                           us1, us2, us3])
+        if self._tzinfo is None:
+            return (basestate,)
+        else:
+            return (basestate, self._tzinfo)
+
+    def __setstate(self, string, tzinfo):
+        if tzinfo is not None and not isinstance(tzinfo, _tzinfo_class):
+            raise TypeError("bad tzinfo state arg")
+        (yhi, ylo, m, self._day, self._hour,
+         self._minute, self._second, us1, us2, us3) = string
+        if m > 127:
+            self._fold = 1
+            self._month = m - 128
+        else:
+            self._fold = 0
+            self._month = m
+        self._year = yhi * 256 + ylo
+        self._microsecond = (((us1 << 8) | us2) << 8) | us3
+        self._tzinfo = tzinfo
+
+    def __reduce_ex__(self, protocol):
+        return (self.__class__, self._getstate(protocol))
+
+    def __reduce__(self):
+        return self.__reduce_ex__(2)
+
+
+datetime.min = datetime(1, 1, 1)
+datetime.max = datetime(9999, 12, 31, 23, 59, 59, 999999)
+datetime.resolution = timedelta(microseconds=1)
+
+
+def _isoweek1monday(year):
+    # Helper to calculate the day number of the Monday starting week 1
+    # XXX This could be done more efficiently
+    THURSDAY = 3
+    firstday = _ymd2ord(year, 1, 1)
+    firstweekday = (firstday + 6) % 7  # See weekday() above
+    week1monday = firstday - firstweekday
+    if firstweekday > THURSDAY:
+        week1monday += 7
+    return week1monday
+
+
+class timezone(tzinfo):
+    __slots__ = '_offset', '_name'
+
+    # Sentinel value to disallow None
+    _Omitted = object()
+    def __new__(cls, offset, name=_Omitted):
+        if not isinstance(offset, timedelta):
+            raise TypeError("offset must be a timedelta")
+        if name is cls._Omitted:
+            if not offset:
+                return cls.utc
+            name = None
+        elif not isinstance(name, str):
+            raise TypeError("name must be a string")
+        if not cls._minoffset <= offset <= cls._maxoffset:
+            raise ValueError("offset must be a timedelta "
+                             "strictly between -timedelta(hours=24) and "
+                             "timedelta(hours=24).")
+        return cls._create(offset, name)
+
+    @classmethod
+    def _create(cls, offset, name=None):
+        self = tzinfo.__new__(cls)
+        self._offset = offset
+        self._name = name
+        return self
+
+    def __getinitargs__(self):
+        """pickle support"""
+        if self._name is None:
+            return (self._offset,)
+        return (self._offset, self._name)
+
+    def __eq__(self, other):
+        if isinstance(other, timezone):
+            return self._offset == other._offset
+        return NotImplemented
+
+    def __hash__(self):
+        return hash(self._offset)
+
+    def __repr__(self):
+        """Convert to formal string, for repr().
+
+        >>> tz = timezone.utc
+        >>> repr(tz)
+        'datetime.timezone.utc'
+        >>> tz = timezone(timedelta(hours=-5), 'EST')
+        >>> repr(tz)
+        "datetime.timezone(datetime.timedelta(-1, 68400), 'EST')"
+        """
+        if self is self.utc:
+            return 'datetime.timezone.utc'
+        if self._name is None:
+            return "%s.%s(%r)" % (self.__class__.__module__,
+                                  self.__class__.__qualname__,
+                                  self._offset)
+        return "%s.%s(%r, %r)" % (self.__class__.__module__,
+                                  self.__class__.__qualname__,
+                                  self._offset, self._name)
+
+    def __str__(self):
+        return self.tzname(None)
+
+    def utcoffset(self, dt):
+        if isinstance(dt, datetime) or dt is None:
+            return self._offset
+        raise TypeError("utcoffset() argument must be a datetime instance"
+                        " or None")
+
+    def tzname(self, dt):
+        if isinstance(dt, datetime) or dt is None:
+            if self._name is None:
+                return self._name_from_offset(self._offset)
+            return self._name
+        raise TypeError("tzname() argument must be a datetime instance"
+                        " or None")
+
+    def dst(self, dt):
+        if isinstance(dt, datetime) or dt is None:
+            return None
+        raise TypeError("dst() argument must be a datetime instance"
+                        " or None")
+
+    def fromutc(self, dt):
+        if isinstance(dt, datetime):
+            if dt.tzinfo is not self:
+                raise ValueError("fromutc: dt.tzinfo "
+                                 "is not self")
+            return dt + self._offset
+        raise TypeError("fromutc() argument must be a datetime instance"
+                        " or None")
+
+    _maxoffset = timedelta(hours=24, microseconds=-1)
+    _minoffset = -_maxoffset
+
+    @staticmethod
+    def _name_from_offset(delta):
+        if not delta:
+            return 'UTC'
+        if delta < timedelta(0):
+            sign = '-'
+            delta = -delta
+        else:
+            sign = '+'
+        hours, rest = divmod(delta, timedelta(hours=1))
+        minutes, rest = divmod(rest, timedelta(minutes=1))
+        seconds = rest.seconds
+        microseconds = rest.microseconds
+        if microseconds:
+            return (f'UTC{sign}{hours:02d}:{minutes:02d}:{seconds:02d}'
+                    f'.{microseconds:06d}')
+        if seconds:
+            return f'UTC{sign}{hours:02d}:{minutes:02d}:{seconds:02d}'
+        return f'UTC{sign}{hours:02d}:{minutes:02d}'
+
+UTC = timezone.utc = timezone._create(timedelta(0))
+
+# bpo-37642: These attributes are rounded to the nearest minute for backwards
+# compatibility, even though the constructor will accept a wider range of
+# values. This may change in the future.
+timezone.min = timezone._create(-timedelta(hours=23, minutes=59))
+timezone.max = timezone._create(timedelta(hours=23, minutes=59))
+_EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)
+
+# Some time zone algebra.  For a datetime x, let
+#     x.n = x stripped of its timezone -- its naive time.
+#     x.o = x.utcoffset(), and assuming that doesn't raise an exception or
+#           return None
+#     x.d = x.dst(), and assuming that doesn't raise an exception or
+#           return None
+#     x.s = x's standard offset, x.o - x.d
+#
+# Now some derived rules, where k is a duration (timedelta).
+#
+# 1. x.o = x.s + x.d
+#    This follows from the definition of x.s.
+#
+# 2. If x and y have the same tzinfo member, x.s = y.s.
+#    This is actually a requirement, an assumption we need to make about
+#    sane tzinfo classes.
+#
+# 3. The naive UTC time corresponding to x is x.n - x.o.
+#    This is again a requirement for a sane tzinfo class.
+#
+# 4. (x+k).s = x.s
+#    This follows from #2, and that datetime.timetz+timedelta preserves tzinfo.
+#
+# 5. (x+k).n = x.n + k
+#    Again follows from how arithmetic is defined.
+#
+# Now we can explain tz.fromutc(x).  Let's assume it's an interesting case
+# (meaning that the various tzinfo methods exist, and don't blow up or return
+# None when called).
+#
+# The function wants to return a datetime y with timezone tz, equivalent to x.
+# x is already in UTC.
+#
+# By #3, we want
+#
+#     y.n - y.o = x.n                             [1]
+#
+# The algorithm starts by attaching tz to x.n, and calling that y.  So
+# x.n = y.n at the start.  Then it wants to add a duration k to y, so that [1]
+# becomes true; in effect, we want to solve [2] for k:
+#
+#    (y+k).n - (y+k).o = x.n                      [2]
+#
+# By #1, this is the same as
+#
+#    (y+k).n - ((y+k).s + (y+k).d) = x.n          [3]
+#
+# By #5, (y+k).n = y.n + k, which equals x.n + k because x.n=y.n at the start.
+# Substituting that into [3],
+#
+#    x.n + k - (y+k).s - (y+k).d = x.n; the x.n terms cancel, leaving
+#    k - (y+k).s - (y+k).d = 0; rearranging,
+#    k = (y+k).s - (y+k).d; by #4, (y+k).s == y.s, so
+#    k = y.s - (y+k).d
+#
+# On the RHS, (y+k).d can't be computed directly, but y.s can be, and we
+# approximate k by ignoring the (y+k).d term at first.  Note that k can't be
+# very large, since all offset-returning methods return a duration of magnitude
+# less than 24 hours.  For that reason, if y is firmly in std time, (y+k).d must
+# be 0, so ignoring it has no consequence then.
+#
+# In any case, the new value is
+#
+#     z = y + y.s                                 [4]
+#
+# It's helpful to step back at look at [4] from a higher level:  it's simply
+# mapping from UTC to tz's standard time.
+#
+# At this point, if
+#
+#     z.n - z.o = x.n                             [5]
+#
+# we have an equivalent time, and are almost done.  The insecurity here is
+# at the start of daylight time.  Picture US Eastern for concreteness.  The wall
+# time jumps from 1:59 to 3:00, and wall hours of the form 2:MM don't make good
+# sense then.  The docs ask that an Eastern tzinfo class consider such a time to
+# be EDT (because it's "after 2"), which is a redundant spelling of 1:MM EST
+# on the day DST starts.  We want to return the 1:MM EST spelling because that's
+# the only spelling that makes sense on the local wall clock.
+#
+# In fact, if [5] holds at this point, we do have the standard-time spelling,
+# but that takes a bit of proof.  We first prove a stronger result.  What's the
+# difference between the LHS and RHS of [5]?  Let
+#
+#     diff = x.n - (z.n - z.o)                    [6]
+#
+# Now
+#     z.n =                       by [4]
+#     (y + y.s).n =               by #5
+#     y.n + y.s =                 since y.n = x.n
+#     x.n + y.s =                 since z and y are have the same tzinfo member,
+#                                     y.s = z.s by #2
+#     x.n + z.s
+#
+# Plugging that back into [6] gives
+#
+#     diff =
+#     x.n - ((x.n + z.s) - z.o) =     expanding
+#     x.n - x.n - z.s + z.o =         cancelling
+#     - z.s + z.o =                   by #2
+#     z.d
+#
+# So diff = z.d.
+#
+# If [5] is true now, diff = 0, so z.d = 0 too, and we have the standard-time
+# spelling we wanted in the endcase described above.  We're done.  Contrarily,
+# if z.d = 0, then we have a UTC equivalent, and are also done.
+#
+# If [5] is not true now, diff = z.d != 0, and z.d is the offset we need to
+# add to z (in effect, z is in tz's standard time, and we need to shift the
+# local clock into tz's daylight time).
+#
+# Let
+#
+#     z' = z + z.d = z + diff                     [7]
+#
+# and we can again ask whether
+#
+#     z'.n - z'.o = x.n                           [8]
+#
+# If so, we're done.  If not, the tzinfo class is insane, according to the
+# assumptions we've made.  This also requires a bit of proof.  As before, let's
+# compute the difference between the LHS and RHS of [8] (and skipping some of
+# the justifications for the kinds of substitutions we've done several times
+# already):
+#
+#     diff' = x.n - (z'.n - z'.o) =           replacing z'.n via [7]
+#             x.n  - (z.n + diff - z'.o) =    replacing diff via [6]
+#             x.n - (z.n + x.n - (z.n - z.o) - z'.o) =
+#             x.n - z.n - x.n + z.n - z.o + z'.o =    cancel x.n
+#             - z.n + z.n - z.o + z'.o =              cancel z.n
+#             - z.o + z'.o =                      #1 twice
+#             -z.s - z.d + z'.s + z'.d =          z and z' have same tzinfo
+#             z'.d - z.d
+#
+# So z' is UTC-equivalent to x iff z'.d = z.d at this point.  If they are equal,
+# we've found the UTC-equivalent so are done.  In fact, we stop with [7] and
+# return z', not bothering to compute z'.d.
+#
+# How could z.d and z'd differ?  z' = z + z.d [7], so merely moving z' by
+# a dst() offset, and starting *from* a time already in DST (we know z.d != 0),
+# would have to change the result dst() returns:  we start in DST, and moving
+# a little further into it takes us out of DST.
+#
+# There isn't a sane case where this can happen.  The closest it gets is at
+# the end of DST, where there's an hour in UTC with no spelling in a hybrid
+# tzinfo class.  In US Eastern, that's 5:MM UTC = 0:MM EST = 1:MM EDT.  During
+# that hour, on an Eastern clock 1:MM is taken as being in standard time (6:MM
+# UTC) because the docs insist on that, but 0:MM is taken as being in daylight
+# time (4:MM UTC).  There is no local time mapping to 5:MM UTC.  The local
+# clock jumps from 1:59 back to 1:00 again, and repeats the 1:MM hour in
+# standard time.  Since that's what the local clock *does*, we want to map both
+# UTC hours 5:MM and 6:MM to 1:MM Eastern.  The result is ambiguous
+# in local time, but so it goes -- it's the way the local clock works.
+#
+# When x = 5:MM UTC is the input to this algorithm, x.o=0, y.o=-5 and y.d=0,
+# so z=0:MM.  z.d=60 (minutes) then, so [5] doesn't hold and we keep going.
+# z' = z + z.d = 1:MM then, and z'.d=0, and z'.d - z.d = -60 != 0 so [8]
+# (correctly) concludes that z' is not UTC-equivalent to x.
+#
+# Because we know z.d said z was in daylight time (else [5] would have held and
+# we would have stopped then), and we know z.d != z'.d (else [8] would have held
+# and we have stopped then), and there are only 2 possible values dst() can
+# return in Eastern, it follows that z'.d must be 0 (which it is in the example,
+# but the reasoning doesn't depend on the example -- it depends on there being
+# two possible dst() outcomes, one zero and the other non-zero).  Therefore
+# z' must be in standard time, and is the spelling we want in this case.
+#
+# Note again that z' is not UTC-equivalent as far as the hybrid tzinfo class is
+# concerned (because it takes z' as being in standard time rather than the
+# daylight time we intend here), but returning it gives the real-life "local
+# clock repeats an hour" behavior when mapping the "unspellable" UTC hour into
+# tz.
+#
+# When the input is 6:MM, z=1:MM and z.d=0, and we stop at once, again with
+# the 1:MM standard time spelling we want.
+#
+# So how can this break?  One of the assumptions must be violated.  Two
+# possibilities:
+#
+# 1) [2] effectively says that y.s is invariant across all y belong to a given
+#    time zone.  This isn't true if, for political reasons or continental drift,
+#    a region decides to change its base offset from UTC.
+#
+# 2) There may be versions of "double daylight" time where the tail end of
+#    the analysis gives up a step too early.  I haven't thought about that
+#    enough to say.
+#
+# In any case, it's clear that the default fromutc() is strong enough to handle
+# "almost all" time zones:  so long as the standard offset is invariant, it
+# doesn't matter if daylight time transition points change from year to year, or
+# if daylight time is skipped in some years; it doesn't matter how large or
+# small dst() may get within its bounds; and it doesn't even matter if some
+# perverse time zone returns a negative dst()).  So a breaking case must be
+# pretty bizarre, and a tzinfo subclass can override fromutc() if it is.
+
+try:
+    from _datetime import *
+except ImportError:
+    pass
+else:
+    # Clean up unused names
+    del (_DAYNAMES, _DAYS_BEFORE_MONTH, _DAYS_IN_MONTH, _DI100Y, _DI400Y,
+         _DI4Y, _EPOCH, _MAXORDINAL, _MONTHNAMES, _build_struct_time,
+         _check_date_fields, _check_time_fields,
+         _check_tzinfo_arg, _check_tzname, _check_utc_offset, _cmp, _cmperror,
+         _date_class, _days_before_month, _days_before_year, _days_in_month,
+         _format_time, _format_offset, _index, _is_leap, _isoweek1monday, _math,
+         _ord2ymd, _time, _time_class, _tzinfo_class, _wrap_strftime, _ymd2ord,
+         _divide_and_round, _parse_isoformat_date, _parse_isoformat_time,
+         _parse_hh_mm_ss_ff, _IsoCalendarDate, _isoweek_to_gregorian,
+         _find_isoformat_datetime_separator, _FRACTION_CORRECTION,
+         _is_ascii_digit)
+    # XXX Since import * above excludes names that start with _,
+    # docstring does not get overwritten. In the future, it may be
+    # appropriate to maintain a single module level docstring and
+    # remove the following line.
+    from _datetime import __doc__