anchor.diff:    // A short message about the status.
     final String statusInfo;
     final List<ValidationMessage> messages;
  -
  -  bool get isInstalled => type == ValidationType.installed;
   
     String get leadingBox {
       if (type == ValidationType.missing)
  
positive.code:   }
  }
  
  class AtomValidator extends DoctorValidator {
    AtomValidator() : super('Atom - a lightweight development environment for Flutter');
  
    static File getConfigFile() {
      // ~/.atom/config.cson
  
negative.code:       : path.join(env['HOME'], '.atom');
    }
  
    bool get isInstalled => FileSystemEntity.isDirectorySync(_getAtomHomePath());
  
    @override
    Future<ValidationResult> validate() async {
      List<ValidationMessage> messages = <ValidationMessage>[];
  
      int installCount = 0;
  
      if (_validateHasPackage(messages, 'flutter', 'Flutter'))
        installCount++;
  
      if (_validateHasPackage(messages, 'dartlang', 'Dart'))
        installCount++;
  
      return new ValidationResult(
        installCount == 2 ? ValidationType.installed : ValidationType.partial,
        messages
      );
    }
  