code: def LookupGrad(op, dval):
      _, k = op.inputs
      map_grad = empty_tensor_map()
      map_grad = tensor_map_insert(map_grad, k, dval)
      key_grad = None
      return map_grad, key_grad
  
file_path: tensorflow-upstream/tensorflow/python/ops/map_ops.py
imports: from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import cond
  from tensorflow.python.ops import gen_map_ops
  from tensorflow.python.ops.gen_map_ops import *
label_desc: Use image node_id 8 for calling a global function with example usage: LookupGrad(op, dval) and returns: map_grad,  key_grad