code: def test_encode_mp3_mono():
      """test_encode_mp3_mono"""
      path = os.path.join(
          os.path.dirname(os.path.abspath(__file__)),
          "test_audio",
          "mono_10khz.wav",
      )
      audio = tfio.audio.decode_wav(
          tf.io.read_file(path), dtype=tf.int16
      )
      assert audio.shape == [5760, 1]
      audio = tf.cast(audio, tf.float32) / 32768.0
      _ = tfio.audio.encode_mp3(audio, rate=8000)
  
imports: import os
  import sys
  import pytest
  import numpy
  import tensorflow
  import tensorflow_io
label_desc: Use image node_id 28 for calling a global function with example usage: test_encode_mp3_mono() without return types