code: function _match(elm, selector)
      {
          if (!selector) {
              return true;
          }
  
          var tag = selector.uTag,
              id = selector.id,
              classes = selector.classes;
  
          return (elm.nodeType === 1) &&
          !(tag && tag !== elm.tagName) &&
          !(id && id !== elm.id) &&
          !(classes && !_hasClasses(elm, classes));
      }
docs: return false if elm is not an Element.
  if selector is undefined/null, then we always match (unless elm is not an Element)
  otherwise we try to match the selector