code: def get_chunk_ref_counts(self, chunk_keys: List[str]) -> List[int]:
      return [
          self._chunk_ref_counts[chunk_key] for chunk_key in chunk_keys
      ]
  
imports: import asyncio
  import itertools
  import logging
  from collections import defaultdict
  from typing import Dict, List, Optional
  from ....None import oscar
  from ....lib.aio import alru_cache
  from ...meta.api import MetaAPI
  from ...storage.api import StorageAPI
  from ..errors import TileableNotTracked
label_desc: Use image node_id 7 for calling the LifecycleTrackerActor obj's underlying member method code with example usage: obj.get_chunk_ref_counts(chunk_keys) and returns: unknown