Update design_prototype_decent.py

Test // | Game | Help | Quit
Welcome to the application  
>>> game                    
Test // | Main | Help       
Let us play this game       
>>> CTRL+C                  
WARNING: Cannot quit in this mode "Game"
Test // | Main | Help                   
Let us play this game                   
>>> main                                
Test // | Game | Help | Quit            
Welcome to the application              
>>> help                                
Test // | Main                          
This is how you use this application    
>>> CTRL+C                              
WARNING: Cannot quit in this mode "Help"
Test // | Main                          
This is how you use this application    
>>> main                                
Test // | Game | Help | Quit            
Welcome to the application              
>>> Bye bye