'Get expiration header named `argument` of queue definition.
Note:
`queue` must be either queue name or options itself.'

def _get_expire(self, queue, argument):

    if isinstance(queue, string_t):
        doc = self.queues.find_one({u'_id': queue})
        if (not doc):
            return
        data = doc[u'options']
    else:
        data = queue
    try:
        value = data[u'arguments'][argument]
    except (KeyError, TypeError):
        return
    return (self.get_now() + datetime.timedelta(milliseconds=value))
