class_docstr: Helper class for async checkpoint.
docstr: Gets or creates the underlying Checkpoint instance.
docstr_tok: ["Gets","or","creates","the","underlying","Checkpoint","instance","."]
code: def checkpointer(self):
      """Gets or creates the underlying Checkpoint instance."""
      if self._checkpoint is None:
          self._checkpoint = self._checkpointer_impl(
              **self._checkpoint_items
          )
      return self._checkpoint
  
imports: import atexit
  import copy
  import queue
  import threading
  import time
  import weakref
  from absl import logging
  from tensorflow.python.checkpoint import checkpoint_context
  from tensorflow.python.checkpoint import trackable_view
  from tensorflow.python.distribute import device_util
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.eager import executor
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import variables
  from tensorflow.python.saved_model.pywrap_saved_model import metrics
  from tensorflow.python.trackable import base
  from tensorflow.python.util import object_identity
label_desc: Use image node_id 3 for calling the AsyncCheckpointHelper obj's underlying member method code with example usage: obj.checkpointer() and returns: self