anchor.diff:  
       font = mkOption {
         default = null;
  -      type = types.nullOr types.string;
  +      type = types.nullOr types.str;
         example = "Droid Sans Mono 14";
         description = "Font to use.";
       };
  
positive.code:     configPath = mkOption {
        default = "${config.xdg.configHome}/rofi/config";
        defaultText = "$XDG_CONFIG_HOME/rofi/config";
        type = types.string;
        description = "Path where to put generated configuration file.";
      };
  
  
negative.code:   cfg = config.programs.rofi;
  
    colorOption = description: mkOption {
      type = types.str;
      description = description;
    };
  
  