def helper_twoarg_comparison(f, unit1, unit2):
    (converters, _) = get_converters_and_unit(f, unit1, unit2)
    return (converters, None)
def helper_twoarg_comparison(f, unit1, unit2):
    (converters, _) = get_converters_and_unit(f, unit1, unit2)
    return (converters, None)