'Adds many activities and serializes them before forwarding
this to add_to_storage
:param activities: the list of activities'

def add_many(self, activities, *args, **kwargs):

    self.metrics.on_feed_write(self.__class__, len(activities))
    serialized_activities = self.serialize_activities(activities)
    return self.add_to_storage(serialized_activities, *args, **kwargs)
