'Return 0 if DST is not in effect, or the DST offset (in minutes
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.'

def dst(self):

    if (self._tzinfo is None):
        return None
    offset = self._tzinfo.dst(self)
    _check_utc_offset('dst', offset)
    return offset
