code: def test(self, audio_file):
      self.model.eval()
      cfg = self.config
      collate_fn_test = self.collate_fn_test
      audio, _ = collate_fn_test.process_utterance(
          audio_file=audio_file, transcript=" "
      )
      audio_len = audio.shape[0]
      audio = paddle.to_tensor(audio, dtype="float32")
      audio_len = paddle.to_tensor(audio_len)
      audio = paddle.unsqueeze(audio, axis=0)
      vocab_list = collate_fn_test.vocab_list
      result_transcripts = self.compute_result_transcripts(
          audio, audio_len, vocab_list, cfg.decoding
      )
      return result_transcripts
  
file_path: PaddleHub/modules/audio/asr/deepspeech2_aishell/deepspeech_tester.py
imports: import os
  import sys
  from pathlib import Path
  import paddle
  from deepspeech.frontend.featurizer.text_featurizer import TextFeaturizer
  from deepspeech.io.collator import SpeechCollator
  from deepspeech.models.ds2 import DeepSpeech2Model
  from deepspeech.utils import mp_tools
  from deepspeech.utils.utility import UpdateConfig
label_desc: Use image node_id 3 for calling the DeepSpeech2Tester obj's underlying member method code with example usage: obj.test(audio_file) and returns: result_transcripts