text: function StringBuilder(s) {
      this._parts = isValue(s) && s !== '' ? [s] : [];
      this.isEmpty = this._parts.length == 0;
  }
  var StringBuilder$ = {
      append: function (s) {
          if (isValue(s) && s !== '') {
              this._parts.push(s);
              this.isEmpty = false;
          }
          return this;
      },
  
      appendLine: function (s) {
          this.append(s);
          this.append('\r\n');
          this.isEmpty = false;
          return this;
      },
  
      clear: function () {
          this._parts = [];
          this.isEmpty = true;
      },
  
      toString: function (s) {
          return this._parts.join(s || '');
      }
  };