const magic = (...rest) => {
	const sum = rest.reduce((acc, current) => acc + current, 0);
	const inner = (...args) => {
		return magic(inner.valueOf(), ...args);
	};

	inner.valueOf = () => sum;

	return inner;
};

magic(5, 2, -9).valueOf();

magic(5, 2, -8)(4) + 2;