code: def test_mono_valid_stereo():
      """valid_audio: mono=True,  y.ndim==2"""
      y = np.zeros((1000, 2)).T
      librosa.util.valid_audio(y, mono=True)
  
imports: import os
  import numpy
  import librosa
  import pytest
label_desc: Use image node_id 1 for calling a global function with example usage: test_mono_valid_stereo() without return types