code: function(cacheNum) {
        if (cacheNum === undefined) {
          cacheNum = 1;
        }
        if (!uuidCache.length) {
          ajax({url: this.urlPrefix + "/_uuids", data: {count: cacheNum}, async:
                false}, {
              success: function(resp) {
                uuidCache = resp.uuids;
              }
            },
            "Failed to retrieve UUID batch."
          );
        }
        return uuidCache.shift();
      }
docs: Fetch a new UUID
  @see <a href="http://techzone.couchbase.com/sites/default/files/
  uploads/all/documentation/couchbase-api-misc.html#couchbase-api-
  misc_uuids_get">docs for /_uuids</a>
  @param {Int} cacheNum Number of uuids to keep cached for future use