Python pygame как мне использовать sprite sheet

 class Mob(pygame.sprite.Sprite): 
    def __init__(self): 
        pygame.sprite.Sprite.__init__(self) 
 
        sheet = pygame.image.load('images/sprite_sheet_character.png') 
        self.image = pygame.transform.scale(sheet, (200, 200)) 
 
        self.rect = self.image.get_rect() 
        self.rect.x = 10 
        self.rect.y = 250 
        self.speedx = 5 
 
    def update(self): 
        self.rect.x += self.speedx