def display_chemin(neurones, bn, screen, pygame):
    """
    dessine le chemin à l'écran
    """
    color = 0, 0, 255
    color2 = 0, 255, 0
    for n in neurones:
        pygame.draw.circle(screen, color, (int(n[0]), int(n[1])), 3)
    v = neurones[bn]
    pygame.draw.circle(screen, color2, (int(v[0]), int(v[1])), 3)
    if len(neurones) > 1:
        pygame.draw.lines(screen, color, True, neurones, 2)
