anchor.diff:        type = types.package;
         default = pkgs.gitlab-runner;
         defaultText = "pkgs.gitlab-runner";
  -      example = literalExample "pkgs.gitlab-runner_1_11";
  +      example = literalExpression "pkgs.gitlab-runner_1_11";
         description = "Gitlab Runner package to use.";
       };
       extraPackages = mkOption {
  
positive.code:         };
        };
        default = { };
        example = literalExample ''
          {
            listenAddress = "0.0.0.0:8093";
          }
  
negative.code:     checkInterval = mkOption {
        type = types.int;
        default = 0;
        example = literalExpression "with lib; (length (attrNames config.services.gitlab-runner.services)) * 3";
        description = ''
          Defines the interval length, in seconds, between new jobs check.
          The default value is 3;
  