code: def plotfft(s, fmax, doplot=False):
      
  
      fs = abs(np.fft.fft(s))
      f = linspace(0, fmax / 2, len(s) / 2)
      if doplot:
          #pl.plot(f[1:int(len(s) / 2)], fs[1:int(len(s) / 2)])
          pass
      return (f[1:int(len(s) / 2)].copy(), fs[1:int(len(s) / 2)].copy())
docs: This functions computes the fft of a signal, returning the frequency
      and their magnitude values.
  
      Parameters
      ----------
      s: array-like
        the input signal.
      fmax: int
        the sampling frequency.
      doplot: boolean
        a variable to indicate whether the plot is done or not.
  
      Returns
      -------
      f: array-like
        the frequency values (xx axis)
      fs: array-like
        the amplitude of the frequency values (yy axis)