(self, dt)
Called before draw during each iteration of
        the event loop. dt is the elapsed time in
        seconds since the last update. OpenGL rendering
        calls are best put in draw() rather than here.
Called before draw during each iteration of
        the event loop. dt is the elapsed time in
        seconds since the last update. OpenGL rendering
        calls are best put in draw() rather than here.
Called before draw during each iteration of the event loop . dt is the elapsed time in seconds since the last update . OpenGL rendering calls are best put in draw () rather than here .
def update(self, dt):
        """
        Called before draw during each iteration of
        the event loop. dt is the elapsed time in
        seconds since the last update. OpenGL rendering
        calls are best put in draw() rather than here.
        """
        pass
def update ( self , dt ) : pass