code: def test_fft_frequencies(sr, n_fft):
      freqs = librosa.fft_frequencies(sr=sr, n_fft=n_fft)
  
      # DC
      assert freqs[0] == 0
  
      # Nyquist, positive here for more convenient display purposes
      assert freqs[-1] == sr / 2.0
  
      # Ensure that the frequencies increase linearly
      dels = np.diff(freqs)
      assert np.allclose(dels, dels[0])
  
imports: import os
  import sys
  import warnings
  import librosa
  import numpy
  import pytest
label_desc: Use image node_id 21 for calling a global function with example usage: test_fft_frequencies(sr, n_fft) without return types