code: def _quantize_grad(op, grad):
      """Clip and binarize tensor using the straight through estimator (STE) for the gradient."""
      return tf.clip_by_value(grad, -1, 1)
  
imports: import numpy
  import tensorflow
  from tensorflow.python.ops.rnn_cell import LSTMStateTuple
  import tensorlayer
  from tensorlayer import logging
  from tensorlayer.decorators import deprecated, deprecated_alias
label_desc: Use image node_id 20 for calling a global function with example usage: _quantize_grad(op, grad) and returns: tf