def helper_two_arg_dimensionless(f, unit1, unit2):
    try:
        converter1 = (get_converter(unit1, dimensionless_unscaled) if (unit1 is not None) else None)
        converter2 = (get_converter(unit2, dimensionless_unscaled) if (unit2 is not None) else None)
    except UnitsError:
        raise UnitTypeError("Can only apply '{0}' function to dimensionless quantities".format(f.__name__))
    return ([converter1, converter2], dimensionless_unscaled)
def helper_two_arg_dimensionless(f, unit1, unit2):
    try:
        converter1 = (get_converter(unit1, dimensionless_unscaled) if (unit1 is not None) else None)
        converter2 = (get_converter(unit2, dimensionless_unscaled) if (unit2 is not None) else None)
    except UnitsError:
        raise UnitTypeError("Can only apply '{0}' function to dimensionless quantities".format(f.__name__))
    return ([converter1, converter2], dimensionless_unscaled)