code: def test_copy_to_mesh(self):
      layout = d_layout.Layout([_BATCH_DIM, "unsharded"], self.mesh)
      host_layout = d_layout.Layout(
          layout.sharding_specs, self.mesh.host_mesh()
      )
      x = d_api.pack(
          [array_ops.ones((2, 2), dtype=dtypes.float32)]
          * len(self.mesh.local_devices()),
          layout,
      )
  
      @polymorphic_function.function
      def d2h(x):
          return d_api.copy_to_mesh(x, host_layout)
  
      @polymorphic_function.function
      def h2d(x):
          return d_api.copy_to_mesh(x, layout)
  
      y = d2h(x)
      ys = d_api.unpack(y)
      for i in ys:
          self.assertAllClose(i, array_ops.ones((2, 2)), atol=1e-5)
      z = h2d(y)
      zs = d_api.unpack(z)
      for i in zs:
          self.assertAllClose(i, array_ops.ones((2, 2)), atol=1e-5)
  
imports: import os
  from absl import flags
  import numpy
  from tensorflow.dtensor.python import accelerator_util
  from tensorflow.dtensor.python import api
  from tensorflow.dtensor.python import config
  from tensorflow.dtensor.python import d_variable
  from tensorflow.dtensor.python import layout
  from tensorflow.dtensor.python import mesh_util
  from tensorflow.dtensor.python.tests import multi_client_test_util
  from tensorflow.dtensor.python.tests import test_backend_util
  from tensorflow.dtensor.python.tests import test_util
  from tensorflow.python.eager import backprop
  from tensorflow.python.eager.polymorphic_function import polymorphic_function
  from tensorflow.python.framework import config
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import nn_ops
  from tensorflow.python.ops import stateless_random_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
label_desc: Use image node_id 4 for calling the DTensorMNISTTest obj's underlying member method code with example usage: obj.test_copy_to_mesh() and returns: d_api, d_api