class_docstr: Storage handler actor, provide methods like `get`, `put`, etc.
  This actor is stateful and created on worker's sub pools.
code: def is_seekable(self, level: StorageLevel):
      if level is None:
          level = self.highest_level
      return self._clients[level].is_seekable
  
imports: import asyncio
  import logging
  from collections import defaultdict
  from typing import Any, Dict, List, Union
  from ...None import oscar
  from ...serialization import AioDeserializer
  from ...storage import StorageLevel, get_storage_backend
  from ...storage.core import StorageFileObject
  from ...typing import BandType
  from ...utils import calc_data_size, lazy_import
  from ..cluster import ClusterAPI, StorageInfo
  from ..meta import MetaAPI
  from .core import StorageQuotaActor, DataManagerActor, DataInfo, build_data_info, WrappedStorageFileObject
  from .errors import DataNotExist, NoDataToSpill
label_desc: Use image node_id 4 for calling the StorageHandlerActor obj's underlying member method code with example usage: obj.is_seekable(level) and returns: self