private boolean findNext() {
            while (childIter.hasNext()) {
                ParseTree nextParseTree = childIter.next();
                if (treeIsSeparator(nextParseTree)) {
                    continue;
                }
                if (!privateNumberRange) {
                    index++;
                }
                if (!isWantedClassPredicate.test(nextParseTree)) {
                    continue;
                }
                if (privateNumberRange) {
                    index++;
                }
                if (index > end) {
                    nextChild = null;
                    return false;
                }
                if (start <= index) {
                    nextChild = nextParseTree;
                    return true;
                }
            }

            // We found nothing
            nextChild = null;
            return false;
        }
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