code: def build_send(self, entity: BaseEntity, from_user: UserType, to_user_key: RsaKey = None) -> Union[str, Dict]:
          
          if hasattr(entity, "outbound_doc") and entity.outbound_doc is not None:
              # Use pregenerated outbound document
              rendered = entity.outbound_doc
          else:
              rendered = entity.to_as2()
          return rendered
docs: Build POST data for sending out to remotes.
  
          :param entity: The outbound ready entity for this protocol.
          :param from_user: The user sending this payload. Must have ``private_key`` and ``id`` properties.
          :param to_user_key: (Optional) Public key of user we're sending a private payload to.
          :returns: dict or string depending on if private or public payload.