code: def testLargeMultiSourceSnapshotRecoversAndCompletes(self):
      n = 5
      cluster, _ = self.setup(
          num_workers=n, ds_size=1000, num_sources=3
      )
      # Blocks until all workers have streams.
      get_stream_assignments(cluster, n, [self._path])
      cluster.stop_worker(0)
      self.assertTrue(
          os.path.exists(
              os.path.join(
                  self._path, "streams", "stream_0", "checkpoints"
              )
          )
      )
  
      cluster.restart_dispatcher()
      cluster.restart_worker(0)
      self._wait_for_snapshot()
      self.assertTrue(self._snapshot_is_done())
  
imports: import collections
  import os
  import pathlib
  import shutil
  import tempfile
  import time
  from absl.testing import parameterized
  from tensorflow.python.data.experimental.kernel_tests.service import test_base
  from tensorflow.python.data.experimental.ops import distributed_save_op
  from tensorflow.python.data.experimental.service import _pywrap_snapshot_utils
  from tensorflow.python.data.kernel_tests import test_base
  from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.data.ops import test_mode
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import errors
  from tensorflow.python.platform import test
label_desc: Use image node_id 20 for calling the SnapshotFtTest obj's underlying member method code with example usage: obj.testLargeMultiSourceSnapshotRecoversAndCompletes() without return types