code: def __getitem__(self, key):
      return self.children[key]
  
imports: import itertools
  from collections.abc import Sequence
  from typing import List, Optional, Set, Tuple, Union
  import torch
label_desc: Use image node_id 2 for calling the AdapterCompositionBlock obj's underlying member method code with example usage: obj.__getitem__(key) and returns: self