docstr: Test that callbacks that return None works.
docstr_tok: ["Test","that","callbacks","that","return","None","works","."]
code: def testSimpleGraphConstructionWithCallbackReturningNone(self):
      """Test that callbacks that return None works."""
      op_types = []
  
      def no_return_callback(
          op_type, inputs, attrs, outputs, op_name=None, graph=None
      ):
          del inputs, attrs, outputs, op_name, graph  # Unused.
          op_types.append(compat.as_bytes(op_type))
  
      op_callbacks.add_op_callback(no_return_callback)
  
      @def_function.function
      def log1p(x):
          return math_ops.log(1.0 + x)
  
      x = constant_op.constant(3.0)
      y = log1p(x)
  
      self.assertAllClose(y, np.log(4.0))
      self.assertIn(_ADD_OP, op_types)
      self.assertIn(_LOG_OP, op_types)
  
imports: import threading
  import numpy
  from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.eager import backprop
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.eager import test
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import op_callbacks
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import script_ops
  from tensorflow.python.ops import sparse_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.util import compat
label_desc: Use image node_id 10 for calling the OpCallbacksTest obj's underlying member method code with example usage: obj.testSimpleGraphConstructionWithCallbackReturningNone() and returns: math_ops