@ValidateLarchPlugin
def xray_lines(element, initial_level=None, excitation_energy=None,
               _larch=None):
    xdb = get_xraydb(_larch)
    return xdb.xray_lines(element, initial_level=initial_level,
                          excitation_energy=excitation_energy)
returns dictionary of x-ray emission lines of an element, with
dataset/ETHPy150Open xraypy/xraylarch/plugins/xray/xraydb_plugin.py/xray_lines