code: def _VocabFormat(self):
      return "tfrecord_gzip"
  
imports: from tensorflow_transform.beam import vocabulary_integration_test
  from tensorflow_transform.beam import tft_unit
label_desc: Use image node_id 1 for calling the TFRecordVocabularyIntegrationTest obj's underlying member method code with example usage: obj._VocabFormat() and returns: str