code: def model(self):
          
          if self.z == 0:
              m = self._model
          else:
              # wavelength
              if self._internal_wave_unit.physical_type == 'length':
                  rs = self._redshift_model.inverse
              # frequency or wavenumber
              # NOTE: This will never execute as long as internal wavelength
              #       unit remains Angstrom.
              else:  # pragma: no cover
                  rs = self._redshift_model
  
              if self.z_type == 'wavelength_only':
                  m = rs | self._model
              else:  # conserve_flux
                  m = rs | self._model | self._redshift_flux_model
  
          return m
docs: Model of the spectrum with given redshift.