docs: function(d) {
        if (!d.isCaching && d.addEventListener) {
          // FireFox/Opera/Safari/KHTML have support for Mutation Events
          d.addEventListener('DOMAttrModified', mutationWrapper, true);
          d.addEventListener('DOMNodeInserted', mutationWrapper, true);
          d.addEventListener('DOMNodeRemoved',  mutationWrapper, true);
          d.isCaching = true;
        }
      }