static fromGenerator(generatorFunction) {
        return new Seq(generatorFunction, true);
    }
Creates a re-usable iterable from a generator function like <code>function*() { yield 1; }</code>.

Note that the obvious alternative, <code>new Seq(function*(){yield 1;}()}</code>, stops working after the
iterable has been iterated once.

@param {!function() : Iterator.<T>} generatorFunction
@returns {!Seq.<T>}
@template T