class_docstr: Block prefetcher using ray.wait.
class_docstr_tok: ["Block","prefetcher","using","ray.wait","."]
code: def __del__(self):
      self.stop()
  
imports: import logging
  import threading
  from contextlib import nullcontext
  from typing import Any, Callable, Iterator, List, Optional, Tuple
  import ray
  from ray.actor import ActorHandle
  from ray.data._internal.batcher import Batcher, ShufflingBatcher
  from ray.data._internal.block_batching.interfaces import Batch, BlockPrefetcher, CollatedBatch
  from ray.data._internal.stats import DatasetStats
  from ray.data.block import Block, BlockAccessor, DataBatch
  from ray.types import ObjectRef
  from ray.util.scheduling_strategies import NodeAffinitySchedulingStrategy
label_desc: Use image node_id 5 for calling the WaitBlockPrefetcher obj's underlying member method code with example usage: obj.__del__() without return types