Create a new pivot attachement record.

def _create_attach_record(self, id, timed):
        """
        Create a new pivot attachement record.
        """
        record = {}

        record[self._foreign_key] = self._parent.get_key()

        record[self._other_key] = id

        if timed:
            record = self._set_timestamps_on_attach(record)

        return record