code: def __len__(self):
      return len(self._dict)
  
imports: from __future__ import annotations
  from collections.abc import Iterable, Sequence
  from typing import TYPE_CHECKING, Any
  import dask
  from dask.base import is_dask_collection, tokenize
  from dask.highlevelgraph import HighLevelGraph
  from dask.layers import Layer
  from distributed.shuffle._arrow import check_minimal_arrow_version
  from distributed.shuffle._core import ShuffleId, barrier_key, get_worker_plugin
  from distributed.shuffle._shuffle import shuffle_barrier, shuffle_transfer
label_desc: Use image node_id 9 for calling the HashJoinP2PLayer obj's underlying member method code with example usage: obj.__len__() and returns: len