@ValidateLarchPlugin
def f0(ion, q, _larch=None):
    xdb = get_xraydb(_larch)
    return xdb.f0(ion, q)
recursivelly traverse directory and store it in format
dataset/ETHPy150Open xraypy/xraylarch/plugins/xray/xraydb_plugin.py/f0--crossover with--dataset/ETHPy150Open ella/citools/tests/test_debian/__init__.py/TestVersionedStatic.store_directory_structure