':param user_id: the id of the user who\'s feed we\'re working on'

def __init__(self, user_id):

    self.user_id = user_id
    self.key_format = self.key_format
    self.key = (self.key_format % {'user_id': self.user_id})
    self.timeline_storage = self.get_timeline_storage()
    self.activity_storage = self.get_activity_storage()
    self._filter_kwargs = dict()
    self._ordering_args = tuple()
