@Override
        public ParseTree next() {
            if (!hasNext()) {
                throw new NoSuchElementException();
            }
            hasNext = null;
            return nextChild;
        }
Find and set the nextChild
@return If there is a next
analyzer/src/main/java/nl/basjes/parse/useragent/analyze/treewalker/steps/walk/stepdown/ChildIterable.java