def set_return_listener(self, cb):
        if cb is not None and not callable(cb):
            raise ValueError('return_listener callback must either be None or '
                             'a callable, but got: %r' % (cb,))
        self._return_listener = cb
Set a callback for basic.return listening. Will be called with a single
dataset/ETHPy150Open agoragames/haigha/haigha/classes/basic_class.py/BasicClass.set_return_listener