code: func NewMockMultifileReader(fetchFiles MockFileFetcher) *MockMultifileReader {
  	var reader EventReader
  	files := fetchFiles()
  	if len(files) == 0 {
  		reader = nil
  	} else {
  		reader = newMockReader(files[0])
  	}
  
  	return &MockMultifileReader{
  		reader:           reader,
  		fetchFiles:       fetchFiles,
  		currentFileIndex: 0,
  		isClosed:         false,
  	}
  }
docs: // There may be more files over time, so the MockFileFetcher is used instead of a static slice of
  // *MockLogFile.