code: def tukey(winlen, alpha):
      
      taper = hann(winlen * alpha)
      rect = np.ones(winlen - len(taper) + 1)
      win = fftconvolve(taper, rect)
      win = win / np.amax(win)
      return win
docs: Generate a tukey (tapered cosine) window
      :param winlen: length of the window, in samples
      :type winlen: int
      :param alpha: proportion of the window to be tapered. 
      0 = rectangular window
      1.0 = hann window
      :type alpha: float