code: function () {
                      var curly, index = parserInput.i;
  
                      if (parserInput.currentChar() === '@' && (curly = parserInput.$re(/^@\{([\w-]+)\}/))) {
                          return new(tree.Variable)('@' + curly[1], index, fileInfo);
                      }
                  }
docs: A variable entity using the protective {} e.g. @{var}