code: def make_energy_bounds_hdu(self, extname="EBOUNDS"):
          
          if self._ebins is None:
              return None
          cols = [fits.Column("CHANNEL", "I", array=np.arange(1, len(self._ebins + 1))),
                  fits.Column("E_MIN", "1E", unit='keV',
                              array=1000 * self._ebins[0:-1]),
                  fits.Column("E_MAX", "1E", unit='keV', array=1000 * self._ebins[1:])]
          hdu = fits.BinTableHDU.from_columns(
              cols, self.make_header(), name=extname)
          return hdu
docs: Builds and returns a FITs HDU with the energy bin boundries
  
          extname   : The HDU extension name