unsupported now. Converting these ops to Functional API op layers was
        unreliable before TF 2.4, and prone to erroring incomprehensibly or
        being silently buggy.
    *   Code that directly asserts on a Keras symbolic value in cases where ops
        like `tf.rank` used to return a static or symbolic value depending on if
        the input had a fully static shape or not. Now these ops always return