code: def gradient_add(grad_1, grad_2, param, verbose=0):
      """
      Sum two gradients
  
      :param grad_1: (TensorFlow Tensor) The first gradient
      :param grad_2: (TensorFlow Tensor) The second gradient
      :param param: (TensorFlow parameters) The trainable parameters
      :param verbose: (int) verbosity level
      :return: (TensorFlow Tensor) the sum of the gradients
      """
      if verbose > 1:
          print([grad_1, grad_2, param.name])
      if grad_1 is None and grad_2 is None:
          return None
      elif grad_1 is None:
          return grad_2
      elif grad_2 is None:
          return grad_1
      else:
          return grad_1 + grad_2
  
imports: import os
  import collections
  import functools
  import multiprocessing
  from typing import Set
  import numpy
  import tensorflow
label_desc: Use image node_id 10 for calling a global function with example usage: gradient_add(grad_1, grad_2, param, verbose) and returns: None, grad_2, grad_1, unknown