code: function () {
                      var name, index = i;
  
                      if (input.charAt(i) === '@' && (name = $(/^@@?[\w-]+/))) {
                          return new(tree.Variable)(name, index, env.currentFileInfo);
                      }
                  }
docs: A Variable entity, such as `@fink`, in  width: @fink + 2px  We use a different parser for variable definitions, see `parsers.variable`.