message: Remove the unnecessary import based on
  `https://github.com/tensorflow/tensorflow/pull/42539#discussion_r485189850`.
diff: @@ -28,7 +28,6 @@ from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_shape
  -from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import clip_ops
  from tensorflow.python.ops import control_flow_ops
  