is singleton design pattern possible in dart code example

Example 1: singleton classes in dart example

class Singleton {
  static Singleton _instance;
  
  Singleton._internal();
  
  static Singleton getInstance() {
    if (_instance == null) {
      _instance = Singleton._internal();
    }
    
    return _instance;
  }
}

Example 2: singleton classes in dart example

class Singleton {
  static Singleton _instance;

  Singleton._internal() {
    _instance = this;
  }

  factory Singleton() => _instance ?? Singleton._internal();
}