message: Expose more private symbols used by other tests.
diff: @@ -26,5 +26,8 @@ from tensorflow.python.tpu.tpu_estimator import _create_global_step
  from tensorflow.python.tpu.tpu_estimator import _export_output_to_tensors
  from tensorflow.python.tpu.tpu_estimator import _get_scaffold
  from tensorflow.python.tpu.tpu_estimator import _Inputs
  +from tensorflow.python.tpu.tpu_estimator import _ITERATIONS_PER_LOOP_VAR
  +from tensorflow.python.tpu.tpu_estimator import _TPU_ENQUEUE_OPS
  from tensorflow.python.tpu.tpu_estimator import _TPU_ESTIMATOR
  +from tensorflow.python.tpu.tpu_estimator import _TPU_TRAIN_OP
  # pylint: enable=wildcard-import,unused-import,redefined-builtin
  