def gauche():
        global direction
        direction = (direction+1) % 4

def droite():
        global direction
        direction = (direction+3) % 4

def avance():
        global direction, x,y
        mettre_bleu(x,y,0)
        x = (x+dx[direction]) % 8
        y = (y+dy[direction]) % 8
        mettre_bleu(x,y,255)

dx = [1,0,-1,0]
dy = [0,1,0,-1]