def to_session_dict(self, next_idx, *args, **kwargs):
     """Returns dict to store on session for partial pipeline."""
     return {
         "next": next_idx,
         "backend": self.AUTH_BACKEND.name,
         "args": tuple(map(model_to_ctype, args)),
         "kwargs": dict((key, model_to_ctype(val)) for key, val in kwargs.iteritems()),
     }

 def to_session_dict(self, next_idx, *args, **kwargs):
     """Returns dict to store on session for partial pipeline."""
     return {
         'next': next_idx,
         'backend': self.AUTH_BACKEND.name,
         'args': tuple(map(model_to_ctype, args)),
         'kwargs': dict((key, model_to_ctype(val))
                             for key, val in kwargs.iteritems())
     }