code: def test_with_multi_process_loading(self, lazy):
      readers = {
          "a": PlainTextReader(),
          "b": PlainTextReader(),
          "c": PlainTextReader(),
      }
      reader = InterleavingDatasetReader(readers)
      data_dir = self.FIXTURES_ROOT / "data"
      file_path = {
          "a": data_dir / "babi.txt",
          "b": data_dir / "conll2003.txt",
          "c": data_dir / "conll2003.txt",
      }
      vocab = Vocabulary.from_instances(reader.read(file_path))
      loader = MultiProcessDataLoader(
          reader,
          file_path,
          num_workers=1,
          batch_size=1,
          max_instances_in_memory=2 if lazy else None,
      )
      loader.index_with(vocab)
  
      list(loader.iter_instances())
      list(loader)
  
imports: from typing import Iterable
  import pytest
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.dataset_readers import DatasetReader, InterleavingDatasetReader
  from allennlp.data.data_loaders import MultiProcessDataLoader
  from allennlp.data.fields import TextField
  from allennlp.data.instance import Instance
  from allennlp.data.token_indexers import SingleIdTokenIndexer
  from allennlp.data.tokenizers import SpacyTokenizer
  from allennlp.data.vocabulary import Vocabulary
label_desc: Use image node_id 3 for calling the TestInterleavingDatasetReader obj's underlying member method code with example usage: obj.test_with_multi_process_loading(lazy) without return types