code: def test_rpc_error(self):
      v = variables.Variable(initial_value=0, dtype=dtypes.int64)
  
      @eager_def_function.function(
          input_signature=[tensor_spec.TensorSpec([], dtypes.int64)]
      )
      def assign_add(a):
          v.assign_add(a)
  
      @eager_def_function.function(input_signature=[])
      def read_var():
          return v.value()
  
      port = portpicker.pick_unused_port()
      address = "localhost:{}".format(port)
      server = rpc_ops.GrpcServer(address)
      server.register("assign_add", assign_add)
      server.register("read_var", read_var)
      server.start()
  
      client = rpc_ops.GrpcClient(address, list_registered_methods=True)
  
      # confirm it works as expected when arguments are passed.
      result_or = client.call(
          "assign_add", [variables.Variable(2, dtype=dtypes.int64)]
      )
      self.assertAllEqual(result_or.is_ok(), True)
      result_or = client.call(
          "read_var",
          output_specs=[tensor_spec.TensorSpec([], dtypes.int64)],
      )
      self.assertAllEqual(result_or.is_ok(), True)
      self.assertAllEqual(result_or.get_value(), [2])
      result_or = client.assign_add(
          variables.Variable(2, dtype=dtypes.int64)
      )
      self.assertAllEqual(True, result_or.is_ok())
  
      result_or = client.read_var()
      self.assertAllEqual(True, result_or.is_ok())
      self.assertAllEqual(result_or.get_value(), 4)
  
      # Fails with invalid argument error when no arguments are passed.
      result_or = client.call("assign_add")
      self.assertAllEqual(result_or.is_ok(), False)
      error_code, _ = result_or.get_error()
      self.assertAllEqual(error_code, errors.INVALID_ARGUMENT)
  
      del server
      with self.assertRaises(errors.DeadlineExceededError):
          _ = client.assign_add_blocking(
              variables.Variable(2, dtype=dtypes.int64), timeout_in_ms=1
          )
  
imports: import threading
  import time
  import numpy
  import portpicker
  from tensorflow.python.distribute.experimental.rpc import rpc_ops
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import config
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_spec
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import data_flow_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
  from tensorflow.python.util import nest
label_desc: Use image node_id 14 for calling the RpcOpsTest obj's underlying member method code with example usage: obj.test_rpc_error() and returns: v