code: def initialize_accelerator_system_once(device_type):
      # Initialize the GPU/TPU before creating the mesh.
      # Note that this method will also trigger the creation of the pairing
      # virtual host CPUs, which is needed by dataset and checkpoint.
      if not accelerator_util.is_initialized():
          # TODO(feyu): Add a method in accelerator_util to check the initialized
          # mesh device types.
          accelerator_util.initialize_accelerator_system(
              device_type, experimental_reset_context=True
          )
  
imports: from tensorflow.dtensor.python import accelerator_util
  from tensorflow.dtensor.python import api
  from tensorflow.dtensor.python import input_util
  from tensorflow.dtensor.python import layout
  from tensorflow.python.distribute import cross_device_ops
  from tensorflow.python.distribute import device_util
  from tensorflow.python.distribute import distribute_lib
  from tensorflow.python.distribute import reduce_util
  from tensorflow.python.distribute import values
  from tensorflow.python.eager import context
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_conversion_registry
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import summary_ops_v2
label_desc: Use image node_id 2 for calling a global function with example usage: initialize_accelerator_system_once(device_type) without return types