message: Updating the XLA autoclustering tutorial with the new way to check for GPUs and also added a printout of time in the non-XLA case to compare against the XLA case.
diff: "import tensorflow as tf\n",
  "\n",
  "# Check that GPU is available: cf. https://colab.research.google.com/notebooks/gpu.ipynb\n",
  - "assert(tf.test.is_gpu_available())\n",
  + "assert(tf.test.gpu_device_name())\n",
  "\n",
  "tf.keras.backend.clear_session()\n",
  "tf.config.optimizer.set_jit(False) # Start with XLA disabled.\n",
  " model.set_weights(initial_weights)\n",
  "\n",
  "warmup(model, x_train, y_train, x_test, y_test)\n",
  - "train_model(model, x_train, y_train, x_test, y_test)\n",
  + "%time train_model(model, x_train, y_train, x_test, y_test)\n",
  "\n",
  "scores = model.evaluate(x_test, y_test, verbose=1)\n",
  "print('Test loss:', scores[0])\n",
  