docs: def _other_to_dict(self, other):
      """When serializing models, this allows attached models (children, parents, etc.) to also be
      serialized.
      """
      if isinstance(other, ModelBase):
        return other.to_dict()
      elif isinstance(other, list):
        # TODO: what if it's not a list?
        return [self._other_to_dict(i) for i in other]
      else:
        return other