def update(self, dx, dt):
        self.vel += dx
        self.vel *= 0.9

        x,y = self.rect.center
        n_x = x+self.vel

        if n_x <= 0: 
            self.vel = 0.0
            n_x = 0 
        
        if n_x*self.width >= self.SCREEN_WIDTH:
            self.vel = 0.0
            n_x = self.SCREEN_WIDTH-self.width

        self.rect.center = (n_x, y)
dataset/ETHPy150Open ntasfi/PyGame-Learning-Environment/ple/games/catcher.py/Paddle.update/operator `+` -> `*`