code: def test_valid_mono():
      """valid_audio: mono=True,  y.ndim==1"""
      y = np.zeros(1000)
      librosa.util.valid_audio(y, mono=True)
  
imports: import os
  import numpy
  import librosa
  import pytest
label_desc: Use image node_id 5 for calling a global function with example usage: test_valid_mono() without return types