cpython/Mac/PythonLauncher/Python Launcher.app/Contents/Resources/English.lproj/MainMenu.nib/classes.nib

{
    IBClasses = (
        {CLASS = FirstResponder; LANGUAGE = ObjC; SUPERCLASS = NSObject; }, 
        {
            ACTIONS = {showPreferences = id; }; 
            CLASS = MyAppDelegate; 
            LANGUAGE = ObjC; 
            SUPERCLASS = NSObject; 
        }
    ); 
    IBVersion = 1; 
}