1.  To switch tf.keras to use Keras 2 (tf-keras), set the environment
        variable TF_USE_LEGACY_KERAS=1 directly or in your python program by
        import os;os.environ["TF_USE_LEGACY_KERAS"]=1. Please note that this
        will set it for all packages in your Python runtime program

*   1.  Change import of keras from tensorflow as follows