code: def __iter__(self):
      return (instance for instance in self._instances)
  
file_path: allennlp/tests/data/samplers/sampler_test.py
imports: from typing import List, Iterable, Dict, Union
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data import Vocabulary, Instance, Token, Batch, DatasetReader
  from allennlp.data.fields import TextField
  from allennlp.data.token_indexers import SingleIdTokenIndexer
label_desc: Use image node_id 2 for calling the LazyIterable obj's underlying member method code with example usage: obj.__iter__() and returns: unknown