static naturals() {
        return Seq.fromGenerator(function*() {
            let i = 0;
            //noinspection InfiniteLoopJS
            while (true) { //eslint-disable-line no-constant-condition
                yield i;
                i++;
            }
        })
    }
Returns the sequence of natural numbers, starting at 0 and incrementing without bound.
@returns {!Seq.<!int>}