docs: function (options) {
          var opts = options || {},
              attrTag = opts.attrTag,
              textTag = opts.textTag || '#text',
              xmlDeclaration = opts.xmlDeclaration || '<?xml version="1.0"?>';
          if (attrTag === undefined) {
              attrTag = '@';
          }
          this.attrTag = attrTag;
          this.attrTagIndex = this.attrTag.length;
          this.textTag = textTag;
          this.xmlDeclaration = xmlDeclaration;
      }