code: def _register_guided_gradient(name):
      if name not in ops._gradient_registry._registry:
  
          @tf.RegisterGradient(name)
          def _guided_backprop(op, grad):
              dtype = op.outputs[0].dtype
              gate_g = tf.cast(grad > 0.0, dtype)
              gate_y = tf.cast(op.outputs[0] > 0.0, dtype)
              return gate_y * gate_g * grad
  
file_path: keras-vis/vis/backend/tensorflow_backend.py
imports: from __future__ import absolute_import
  import os
  import tempfile
  import inspect
  import numpy
  import tensorflow
  from ..utils import utils
  from tensorflow.python.framework import ops
  import keras
  from keras.models import load_model
  from keras.layers import advanced_activations, Activation
label_desc: Use image node_id 1 for calling a global function with example usage: _register_guided_gradient(name) and returns: unknown