'Iterate over the followers of this user.
:param int number: (optional), number of followers to return. Default:
-1 returns all available
:param str etag: (optional), ETag from a previous request to the same
endpoint
:returns: generator of :class:`User <User>`\ s'

def followers(self, number=(-1), etag=None):

    url = self._build_url(u'followers', base_url=self._api)
    return self._iter(int(number), url, ShortUser, etag=etag)
