anchor.diff:  }
   
   abstract class PlatformFlags {
  -  /// Denotes a package that references Flutter in `pubspec.yaml`.
  +  /// Package uses or depends on Flutter.
     static const String flutter = 'flutter';
   
  -  /// Denotes a library that depends on a native extensions via `dart-ext:`
  +  /// Package uses or depends on a native extensions via `dart-ext:`
     static const String dartExtension = 'dart-ext';
  +
  +  /// Package works everywhere.
  +  static const String everywhere = 'everywhere';
  +
  +  /// Package's platform is unspecified.
  +  static const String undefined = 'undefined';
  +
  +  /// Package's dependencies are in conflict, won't work.
  +  static const String conflict = 'conflict';
  +
  +  /// Package is available in server applications.
  +  static const String server = 'server';
  +
  +  /// Package is available in web applications.
  +  static const String web = 'web';
   }
   
   @JsonSerializable()
  
positive.code: 
    factory PubspecPlatform.fromJson(String value) {
      switch (value) {
        case 'flutter':
          return flutter;
        case 'undefined':
          return undefined;
        default:
          throw new ArgumentError.value(value, 'value', 'Not a supported value.');
  
negative.code: class PubspecPlatform {
    final String description;
  
    static const PubspecPlatform flutter =
        const PubspecPlatform._(PlatformFlags.flutter);
  
    static const PubspecPlatform undefined =
        const PubspecPlatform._(PlatformFlags.undefined);
  
    bool get isFlutter => description == flutter.description;
  
  