code: def pivot_wavelength_ee(bpass):
      
      from scipy.integrate import simps
      return np.sqrt(simps(bpass.resp, bpass.wlen) /
                     simps(bpass.resp / bpass.wlen**2, bpass.wlen))
docs: Compute pivot wavelength assuming equal-energy convention.
  
      `bpass` should have two properties, `resp` and `wlen`. The units of `wlen`
      can be anything, and `resp` need not be normalized in any particular way.