<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def optimizer_tensor(self) -> Union[tf.Tensor, tf.Operation]: """ The `optimizer_tensor` is an attribute for getting optimization's optimizer tensor. """

        return _get_attr(self, _optimizer_tensor=None)