code: def __getitem__(self, __key: Any) -> Any:
      return self._data[__key]
  
imports: import math
  from contextlib import contextmanager
  from datetime import datetime
  from typing import Any, Dict, Iterator, MutableMapping
  from pytest import fixture, raises, warns
  from neptune import init_run
  from neptune.common.warnings import NeptuneUnsupportedType, warned_once
  from neptune.constants import MAX_32_BIT_INT, MIN_32_BIT_INT
  from neptune.types import Artifact, Boolean, Datetime, Float, FloatSeries, Integer, String, StringSeries
  from neptune.utils import stringify_unsupported
label_desc: Use image node_id 4 for calling the CustomMutableMapping obj's underlying member method code with example usage: obj.__getitem__(__key) and returns: self