'Check if the authenticated user is following login.
:param str username: (required), login of the user to check if the
authenticated user is checking
:returns: bool'

@requires_auth
def is_following(self, username):

    json = False
    if username:
        url = self._build_url(u'user', u'following', username)
        json = self._boolean(self._get(url), 204, 404)
    return json
