# File lib/xml/dom/core.rb, line 559
      def insertBefore(newChild, refChild)
        if @children.nil? || @children.length == 0
          raise DOMException.new(DOMException::NOT_FOUND_ERR)
        end
        index = _getChildIndex(refChild)
        raise DOMException.new(DOMException::NOT_FOUND_ERR) if !index
        _insertNodes(index, newChild)
      end