public class EagerSingleton
        {
            private static readonly EagerSingleton instance = new EagerSingleton();
            private EagerSingleton(){}
            public static EagerSingleton GetInstance()
            {
                return instance;
            }
        }

        public class LazySingleton
        {
            private static LazySingleton instance = null;
            private LazySingleton(){}
            public static LazySingleton GetInstance()
            {
                if (instance == null)
                {
                    instance = new LazySingleton();
                }
                return instance;
            }
        }