Method poll

src/main/java/pascal/taie/util/collection/SetQueue.java:60–70

()

    }

    @Override
    public E poll() {
        Iterator<E> it = set.iterator();
        if (it.hasNext()) {
            E e = it.next();
            it.remove();
            return e;
        } else {
            return null;
        }
    }

    @Override
    public E peek() {