code: def speech_recognize(self, audio_file, device="cpu"):
      assert os.path.isfile(audio_file), "File not exists: {}".format(
          audio_file
      )
      self.check_audio(audio_file)
  
      paddle.set_device(device)
      return self.tester.test(audio_file)[0][0]
  
file_path: PaddleHub/modules/audio/asr/u2_conformer_librispeech/module.py
imports: import os
  from pathlib import Path
  import sys
  import numpy
  from paddlehub.env import MODULE_HOME
  from paddlehub.module.module import moduleinfo, serving
  from paddlehub.utils.log import logger
  import paddle
  import soundfile
  from deepspeech.exps.u2.config import get_cfg_defaults
  from deepspeech.utils.utility import UpdateConfig
  from .u2_conformer_tester import U2ConformerTester
label_desc: Use image node_id 3 for calling the U2Conformer obj's underlying member method code with example usage: obj.speech_recognize(audio_file, device) and returns: self