code: def test_deemphasis(coef, zi, return_zf, dtype):
      x = np.arange(10, dtype=dtype)
  
      y = librosa.effects.preemphasis(
          x, coef=coef, zi=zi, return_zf=return_zf
      )
  
      if return_zf:
          y, zf = y
  
      y_deemph = librosa.effects.deemphasis(y, coef=coef, zi=zi)
  
      assert np.allclose(x, y_deemph)
      assert x.dtype == y_deemph.dtype
  
imports: import warnings
  import os
  from contextlib import nullcontext
  import numpy
  import pytest
  import librosa
label_desc: Use image node_id 24 for calling a global function with example usage: test_deemphasis(coef, zi, return_zf, dtype) without return types