def hdu_add_lams(newhdu, refheader):
    """ Adds the wavelength information from a reference header to a new hdu.

   :param newhdu: The destination hdu to which the wavelength keywords must be added.
   :param refheader: The reference header, from which to transer the wavelength keywords.

   :return: FITS HDU, the newheader with wavelength info included.

   .. note:: Keywords transfered are 'CTYPE3', 'CUNIT3', 'CD3_3', 'CRPIX3', 'CRVAL3',
             'CD1_3', 'CD2_3', 'CD3_1' and 'CD3_2'.
   """
    newhdu.header['CTYPE3'] = refheader['CTYPE3']
    newhdu.header['CUNIT3'] = refheader['CUNIT3']
    newhdu.header['CD3_3'] = refheader['CD3_3']
    newhdu.header['CRPIX3'] = refheader['CRPIX3']
    newhdu.header['CRVAL3'] = refheader['CRVAL3']
    newhdu.header['CD1_3'] = refheader['CD1_3']
    newhdu.header['CD2_3'] = refheader['CD2_3']
    newhdu.header['CD3_1'] = refheader['CD3_1']
    newhdu.header['CD3_2'] = refheader['CD3_2']
    return newhdu
