'Removes the activities from the feed on the given key
(The serialization is done by the serializer class)
:param key: the key at which the feed is stored
:param activities: the activities which to remove'

def remove_many(self, key, activities, *args, **kwargs):

    self.metrics.on_feed_remove(self.__class__, len(activities))
    if (activities and isinstance(activities[0], (six.string_types, six.integer_types, uuid.UUID))):
        serialized_activities = {a: a for a in activities}
    else:
        serialized_activities = self.serialize_activities(activities)
    return self.remove_from_storage(key, serialized_activities, *args, **kwargs)
