Fibonnacci

Write a generator function that returns a generator object which yields the fibonacci sequence.

The fibonacci sequence is defined by the relation Xn = Xn-1 + Xn-2.

The first few numbers of the series are 0, 1, 1, 2, 3, 5, 8, 13.

const fibGenerator = function*() {
    let a = 0;
    let b = 1;

    while (true) {
        yield a;
        [a, b] = [b, b + a];
    }
}

const gen = fibGenerator();

gen.next().value; // 0
gen.next().value; // 1