1. package Mouse is 
  2.  
  3.     pragma Pure; 
  4.  
  5.     type Mouse_Button is (Mouse_Left, Mouse_Right, Mouse_Middle); 
  6.  
  7.     -- Returns Mouse_Button 'mb' as a string: "Left", "Right", or "Middle". 
  8.     function To_String( mb : Mouse_Button ) return String; 
  9.  
  10. end Mouse;