class_docstr: Helper actor that prefetches blocks asynchronously.
class_docstr_tok: ["Helper","actor","that","prefetches","blocks","asynchronously","."]
code: def prefetch(self, *blocks) -> None:
      pass
  
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 1 for calling the _BlockPretcher obj's underlying member method code with example usage: obj.prefetch() without return types