code: def _planck(self, lam, Teff):
          
  
          return 2*self.h*self.c*self.c/lam**5 * 1./(np.exp(self.h*self.c/lam/self.k/Teff)-1)
docs: Computes monochromatic blackbody intensity in W/m^3 using the
          Planck function.
  
          @lam: wavelength in m
          @Teff: effective temperature in K
  
          Returns: monochromatic blackbody intensity