import pgzrun

TITLE = "vava bird"
WIDTH = 490
HEIGHT = 490

d = 2

def update():
    global d
    if oiseau.x >= 470 and d > 0:
        d = -d
    if oiseau.x <= 20 and d < 0:
        d = -d
    oiseau.x += d


def draw():
    screen.blit("back", (0, 0))
    oiseau.draw()

oiseau = Actor("bird1", (20, 15))

pgzrun.go()