human
Here's a good function header given the following:
I wrote the below code

    query_time = None
    timestamp = request.get('Timestamp')
    expiry_time = request.get('Expires')
    def parse_strtime(strtime):
        if _ms_time_regex.match(strtime):
            time_format = '%Y-%m-%dT%H:%M:%S.%fZ'
        else:
            time_format = '%Y-%m-%dT%H:%M:%SZ'
        return timeutils.parse_strtime(strtime, time_format)
    try:
        if (timestamp and expiry_time):
            msg = _('Request    must    include    either    Timestamp    or    Expires,    but    cannot    contain    both')
            LOG.error(msg)
            raise exception.InvalidRequest(msg)
        elif expiry_time:
            query_time = parse_strtime(expiry_time)
            return timeutils.is_older_than(query_time, (-1))
        elif timestamp:
            query_time = parse_strtime(timestamp)
            if (query_time and expires):
                return (timeutils.is_older_than(query_time, expires) or timeutils.is_newer_than(query_time, expires))
        return False
    except ValueError:
        LOG.audit(_('Timestamp    is    invalid.'))
        return True

What's a good function header?
assistant
#Here's a good function header.

def is_ec2_timestamp_expired(request, expires=None):