code: def spectral_decrease(signal, fs):
      """Represents the amount of decreasing of the spectra amplitude.
  
      Description and formula in Article:
      The Timbre Toolbox: Extracting audio descriptors from musicalsignals
      Authors Peeters G., Giordano B., Misdariis P., McAdams S.
  
      Feature computational cost: 1
  
      Parameters
      ----------
      signal : nd-array
          Signal from which spectral decrease is computed
      fs : float
          Sampling frequency
  
      Returns
      -------
      float
          Spectral decrease
  
      """
      f, fmag = calc_fft(signal, fs)
  
      fmag_band = fmag[1:]
      len_fmag_band = np.arange(2, len(fmag) + 1)
  
      # Sum of numerator
      soma_num = np.sum(
          (fmag_band - fmag[0]) / (len_fmag_band - 1), axis=0
      )
  
      if not np.sum(fmag_band):
          return 0
      else:
          # Sum of denominator
          soma_den = 1 / np.sum(fmag_band)
  
          # Spectral decrease computing
          return soma_den * soma_num
  
imports: import scipy.signal
  from tsfel.feature_extraction.features_utils import *
label_desc: Use image node_id 42 for calling a global function with example usage: spectral_decrease(signal, fs) and returns: int, unknown