code: def lifter(cepstra, L=22):
      
      if L > 0:
          nframes,ncoeff = numpy.shape(cepstra)
          n = numpy.arange(ncoeff)
          lift = 1 + (L/2.)*numpy.sin(numpy.pi*n/L)
          return lift*cepstra
      else:
          # values of L <= 0, do nothing
          return cepstra
docs: Apply a cepstral lifter the the matrix of cepstra. This has the effect of increasing the
      magnitude of the high frequency DCT coeffs.
  
      :param cepstra: the matrix of mel-cepstra, will be numframes * numcep in size.
      :param L: the liftering coefficient to use. Default is 22. L <= 0 disables lifter.