Internal method to populate the object given the ``id`` or
        ``reference_id`` that has been set in the constructor.

def _find_playlist(self):
        """
        Internal method to populate the object given the ``id`` or
        ``reference_id`` that has been set in the constructor.
        """
        data = None
        if self.id:
            data = self.connection.get_item(
                'find_playlist_by_id', playlist_id=self.id)
        elif self.reference_id:
            data = self.connection.get_item(
                'find_playlist_by_reference_id',
                reference_id=self.reference_id)

        if data:
            self._load(data)