class_docstr: Tests for mesh_util that require accelerator initialization.
class_docstr_tok: ["Tests","for","mesh_util","that","require","accelerator","initialization","."]
code: def test_initialize_after_tensorflow(self):
      accelerator_util.shutdown_accelerator_system()
      context.ensure_initialized()
  
      with self.assertRaisesRegex(
          ValueError, "TensorFlow has already been initialized"
      ):
          accelerator_util.initialize_accelerator_system("CPU")
  
imports: import os
  from unittest import mock
  from absl.testing import parameterized
  from tensorflow.dtensor.python import accelerator_util
  from tensorflow.dtensor.python import config
  from tensorflow.dtensor.python import mesh_util
  from tensorflow.dtensor.python.tests import test_util
  from tensorflow.python.eager import context
  from tensorflow.python.framework import config
  from tensorflow.python.framework import device
  from tensorflow.python.platform import test
label_desc: Use image node_id 7 for calling the InitializedMeshUtilTest obj's underlying member method code with example usage: obj.test_initialize_after_tensorflow() without return types