code: def spline_interpolate(x_axis, y_axis, x_new_axis):
      
      f = interp1d(x_axis, y_axis, kind="cubic")
      return f(x_new_axis)
docs: Interpolate a y = f(x) function using Spline interpolation algorithm, 
      x_new_axis has to be in range of x_axis.
  
      `Spline interpolation <https://en.wikipedia.org/wiki/Spline_interpolation>`_
      is a popular interpolation method. Way more accurate than linear interpolate
      in average