code: def Gaussian(x, a, x0, sigma, y0):
      
      return a * np.exp(-(x - x0) ** 2 / (2 * sigma ** 2)) + y0
docs: Gaussian peak
  
      Inputs:
      -------
          ``x``: independent variable
          ``a``: scaling factor (extremal value)
          ``x0``: center
          ``sigma``: half width at half maximum
          ``y0``: additive constant
  
      Formula:
      --------
          ``a*exp(-(x-x0)^2)/(2*sigma^2)+y0``