code: def test_op_works(self, num_examples: int) -> None:
      seq = list(range(1, 100))
  
      pipeline = read_sequence(seq).prefetch(num_examples).and_return()
  
      for _ in range(2):
          assert list(pipeline) == seq
  
          pipeline.reset()
  
file_path: fairseq2/tests/unit/data/data_pipeline/test_prefetch.py
imports: from itertools import islice
  import pytest
  from fairseq2.data import DataPipelineError, read_sequence
label_desc: Use image node_id 1 for calling the TestPrefetchOp obj's underlying member method code with example usage: obj.test_op_works(num_examples) without return types