// I used this the most often
    public class Singleton1
    {
        public static readonly Singleton1 Instance = new Singleton1();
        
        private Singleton1(){}

        private string _TestProperty;
        public string TestProperty
        {
            get{return _TestProperty;}
            set{_TestProperty = value;}
        }
    }

    //using Method and private static field
    public class Singleton2
    {
        private static Singleton2 _Instance;
        
        private Singleton2(){}

        public static Singleton2 GetInstance()
        {
            if (_Instance==null)
                _Instance = new Singleton2();

            return _Instance;
        }

        private string _TestProperty;
        public string TestProperty
        {
            get{return _TestProperty;}
            set{_TestProperty = value;}
        }
    }
    
    // Created by Singleton3Factory
    public class Singleton3
    {
        protected internal Singleton3(){}
    
        private string _TestProperty;
        public string TestProperty
        {
            get{return _TestProperty;}
            set{_TestProperty = value;}
        }
    }

    //creator of the Singleton3 object
    public class Singleton3Factory
    {

        private static Singleton3 _Instance;

        public static Singleton3 CreateInstance()
        {
            
            if (_Instance==null)
                _Instance = new Singleton3();
            
            return _Instance;
        }
    }