Multiple key strokes

    # --- Game logic should go here
    pressed_key = pygame.key.get_pressed()  
        # Figure out if it was an arrow key. If so
    if pressed_key[pygame.K_LEFT]:
        for i in range(len(snow_list)):
            snow_list[i][0] -= random.randrange(0,15)
    if pressed_key[pygame.K_RIGHT]:
        for i in range(len(snow_list)):
            snow_list[i][0] += random.randrange(0,15)