docs: function(node, tagName, maxDepth, filterFn) {
      maxDepth = maxDepth || 3;
      tagName = tagName.toUpperCase();
      var depth = 0;
      while (node.parentNode) {
        if (maxDepth > 0 && depth > maxDepth)
          return false;
        if (node.parentNode.tagName === tagName && (!filterFn || filterFn(node.parentNode)))
          return true;
        node = node.parentNode;
        depth++;
      }
      return false;
    }