C# Online Compiler | .NET Fiddle

using System;
using System.Collections.Generic;

					
public class Program
{
	public static void Main()
	{
		var history_lesson = new History203Controller();
		history_lesson.gotoA();
		history_lesson.gotoC();
		history_lesson.goBack();
		history_lesson.gotoB();
		history_lesson.gotoC();
		history_lesson.goBack();
	}
}


public class FrameEvent {
	public FrameEvent(String Msg, Dictionary<String,object> Parameters) {
		this.Msg = Msg;
		this.Parameters = Parameters;
	}
	public String Msg;
	public Dictionary<String,Object> Parameters;
	public Object Return;
}


// emitted from framec_v0.3.25
public partial class History203 {
    public History203() {
        
        _state_ = _sWaiting_;
    }
    
    //===================== Interface Block ===================//
    
    public void gotoA() {
        FrameEvent e = new FrameEvent("gotoA",null);
        _state_(e);
    }
    
    public void gotoB() {
        FrameEvent e = new FrameEvent("gotoB",null);
        _state_(e);
    }
    
    public void gotoC() {
        FrameEvent e = new FrameEvent("gotoC",null);
        _state_(e);
    }
    
    public void goBack() {
        FrameEvent e = new FrameEvent("goBack",null);
        _state_(e);
    }
    
    
    //===================== Machine Block ===================//
    
    private void _sWaiting_(FrameEvent e) {
        if (e.Msg.Equals(">")) {
            print_do("In $Waiting");
            return;
        }
        else if (e.Msg.Equals("gotoA")) {
            print_do("|gotoA|");
            _transition_(_sA_);
            return;
        }
        else if (e.Msg.Equals("gotoB")) {
            print_do("|gotoB|");
            _transition_(_sB_);
            return;
        }
    }
    
    private void _sA_(FrameEvent e) {
        if (e.Msg.Equals(">")) {
            print_do("In $A");
            return;
        }
        else if (e.Msg.Equals("gotoB")) {
            print_do("|gotoB|");
            _transition_(_sB_);
            return;
        }
        _sAB_(e);
        
    }
    
    private void _sB_(FrameEvent e) {
        if (e.Msg.Equals(">")) {
            print_do("In $B");
            return;
        }
        else if (e.Msg.Equals("gotoA")) {
            print_do("|gotoA|");
            _transition_(_sA_);
            return;
        }
        _sAB_(e);
        
    }
    
    private void _sAB_(FrameEvent e) {
        if (e.Msg.Equals("gotoC")) {
            print_do("|gotoC| in $AB");
            _stateStack_push_(_state_);
            // $$[+]
            _transition_(_sC_);
            return;
        }
    }
    
    private void _sC_(FrameEvent e) {
        if (e.Msg.Equals(">")) {
            print_do("In $C");
            return;
        }
        else if (e.Msg.Equals("goBack")) {
            print_do("|goBack|");
            // $$[-]
            FrameState state = _stateStack_pop_();
            _transition_(state);
            return;
        }
    }
    
    //===================== Actions Block ===================//
    
    protected virtual void print_do(string msg) { throw new NotImplementedException(); }
    
    
    //=========== Machinery and Mechanisms ===========//
    
    private delegate void FrameState(FrameEvent e);
    private FrameState _state_;
    
    
    private void _transition_(FrameState newState) {
        FrameEvent exitEvent = new FrameEvent("<",null);
        _state_(exitEvent);
        _state_ = newState;
        FrameEvent enterEvent = new FrameEvent(">",null);
        _state_(enterEvent);
    }
    
    private Stack<FrameState> _stateStack_ = new Stack<FrameState>();
    
    private void _stateStack_push_(FrameState state) {
        _stateStack_.Push(state);
    }
    
    private FrameState _stateStack_pop_() {
        return _stateStack_.Pop();
    }
    
}

public partial class History203Controller : History203 {

    protected override void print_do(string msg) {
		Console.WriteLine(msg);
	}   

}

    protected virtual void print_do(string msg) { throw new NotImplementedException(); }
 
using System;
using System.Collections.Generic;
​
                    
public class Program
{
    public static void Main()
    {
        var history_lesson = new History203Controller();
        history_lesson.gotoA();
        history_lesson.gotoC();
        history_lesson.goBack();
        history_lesson.gotoB();
        history_lesson.gotoC();
        history_lesson.goBack();
    }
}
​
​
public class FrameEvent {
    public FrameEvent(String Msg, Dictionary<String,object> Parameters) {
        this.Msg = Msg;
        this.Parameters = Parameters;
    }