Instead of converting probabilities to logits, we are using the cross
        entropy formula for probabilities.
    *   Added public APIs for `cumsum` and `cumprod` keras backend functions.
    *   Add support for temporal sample weight mode in subclassed models.
    *   Raise `ValueError` if an integer is passed to the training APIs.
    *   Added fault-tolerance support for training Keras model via `model.fit()`