code: def testGradientGraphOptimization(self):
      @def_function.function
      def f(x, y):
          with backprop.GradientTape() as tape:
              z = math_ops.mul(x, array_ops.zeros_like(x))
              l = math_ops.add(z, y)
              l = math_ops.reduce_sum(l)
  
          gx, gy = tape.gradient(l, [x, y])
          x.assign_add(gx)
          y.assign_add(gy)
          return x + y
  
      # XLA completely optimizes away the variable reads and
      # assignments, so skip the test.
      if test_util.is_xla_enabled():
          self.skipTest("Not relevant for XLA")
      with context.eager_mode():
          x = resource_variable_ops.ResourceVariable(
              np.random.uniform(size=[2, 2]), dtype=dtypes.float32
          )
          y = resource_variable_ops.ResourceVariable(
              np.random.uniform(size=[2, 2]), dtype=dtypes.float32
          )
          with context.collect_graphs(optimized=True) as graphs:
              f(x, y).numpy()
      self.assertLen(graphs, 1)
      assign_count = 0
      for node in graphs[0].node:
          if node.op == "AssignAddVariableOp":
              self.assertEqual(node.input[0], "y")
              assign_count += 1
  
      # Make sure that the only variable update that remains after
      # grappler optimization is that of y.
      self.assertEqual(assign_count, 1)
      self.assertLen(graphs[0].node, 11)
  
file_path: tensorflow-upstream/tensorflow/python/grappler/constant_folding_test.py
imports: import numpy
  from tensorflow.python.eager import backprop
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import functional_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.ops import while_loop
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling the ConstantFoldingTest obj's underlying member method code with example usage: obj.testGradientGraphOptimization() and returns: unknown