engine.py
def on_quit(self, f_cb):
        """ set on quit callback
            Note: return False to postpone quitting
        """
        self._on_quit_cb = types.MethodType(f_cb, self)
 set on quit callback
            Note: return False to postpone quitting
        
set on quit callback
Note: return False to postpone quitting
set on quit callback Note : return False to postpone quitting
def on_quit(self, f_cb):
        self._on_quit_cb = types.MethodType(f_cb, self)
def on_quit ( self , f_cb ) : self . _on_quit_cb = types . MethodType ( f_cb , self )
set on quit callback
Note: return False to postpone quitting
set on quit callback Note : return False to postpone quitting
""" set on quit callback
            Note: return False to postpone quitting
        """
self
f_cb