superjson/pkg/dateutil/tz/_common.py
def fromutc(self, dt):
        """ Given a datetime in UTC, return 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")

        # Get transitions - if there are none, fixed offset
        transitions = self.transitions(dt.year)
        if transitions is None:
            return dt + self.utcoffset(dt)

        # Get the transition times in UTC
        dston, dstoff = transitions

        dston -= self._std_offset
        dstoff -= self._std_offset

        utc_transitions = (dston, dstoff)
        dt_utc = dt.replace(tzinfo=None)

        isdst = self._naive_isdst(dt_utc, utc_transitions)

        if isdst:
            dt_wall = dt + self._dst_offset
        else:
            dt_wall = dt + self._std_offset

        _fold = int(not isdst and self.is_ambiguous(dt_wall))

        return enfold(dt_wall, fold=_fold)
def fromutc(self, dt):
        """ Given a datetime in UTC, return 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")

        # Get transitions - if there are none, fixed offset
        transitions = self.transitions(dt.year)
        if transitions is None:
            return dt + self.utcoffset(dt)

        # Get the transition times in UTC
        dston, dstoff = transitions

        dston -= self._std_offset
        dstoff -= self._std_offset

        utc_transitions = (dston, dstoff)
        dt_utc = dt.replace(tzinfo=None)

        isdst = self._naive_isdst(dt_utc, utc_transitions)

        if isdst:
            dt_wall = dt + self._dst_offset
        else:
            dt_wall = dt + self._std_offset

        _fold = int(not isdst and self.is_ambiguous(dt_wall))

        return enfold(dt_wall, fold=_fold)
Given a datetime in UTC, return local time