public boolean insert(LinkRelevance linkRelev) {
        if (linkRelev == null) {
            return false;
        }
        boolean inserted = false;
        String url = linkRelev.getURL().toString();
        Double relevance = exist(linkRelev);
        if (relevance == null) {
            urlRelevance.put(url, linkRelev);
            inserted = true;
        }

        return inserted;
    }
This method inserts a new link into the frontier

@param linkRelev
@return
ache/src/main/java/achecrawler/link/frontier/Frontier.java