code: def testGetCheckpointMtimes(self):
      prefixes = []
      for version in (saver_pb2.SaverDef.V2, saver_pb2.SaverDef.V1):
          with self.session(graph=ops_lib.Graph()) as sess:
              unused_v = variables.Variable(1.0, name="v")
              self.evaluate(variables.global_variables_initializer())
              saver = saver_module.Saver(write_version=version)
              prefixes.append(
                  saver.save(
                      sess, os.path.join(self._base_dir, str(version))
                  )
              )
  
      mtimes = checkpoint_management.get_checkpoint_mtimes(prefixes)
      self.assertEqual(2, len(mtimes))
      self.assertTrue(mtimes[1] >= mtimes[0])
  
imports: import contextlib
  import os
  import pathlib
  import shutil
  import tempfile
  from google.protobuf import text_format
  from tensorflow.core.protobuf import saver_pb2
  from tensorflow.python.checkpoint import checkpoint
  from tensorflow.python.checkpoint import checkpoint_management
  from tensorflow.python.eager import context
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.lib.io import file_io
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import gfile
  from tensorflow.python.platform import test
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.training import saver
  from tensorflow.python.training.checkpoint_state_pb2 import CheckpointState
label_desc: Use image node_id 4 for calling the SaverUtilsTest obj's underlying member method code with example usage: obj.testGetCheckpointMtimes() without return types