如何在Pygame中翻转img，在我的代码中遇到问题？

Question

我在pygame中无法翻转精灵（我可以让它向右移动，但我希望img在左键上翻转），
我研究了如何翻转图像并找到了pygame.transform.flip，但是作为pygame的初学者，我不确定如何使用它，而且教程对我来说没有意义。
有谁能帮我完成下面的代码吗（我不确定我是否把self.img1放在了正确的位置）？

import pygame, sys, glob 
from pygame import *

class Player:
    def __init__(self):      
        self.x = 200     
        self.y = 300   
        self.ani_speed_init = 6
        self.ani_speed = self.ani_speed_init 
        self.ani = glob.glob("walk\Pinks_w*.png")
        self.ani.sort() 
        self.ani_pos = 0
        self.ani_max = len(self.ani)-1
        self.img = pygame.image.load(self.ani[0])
        self.img1 = pygame.transform.flip(self.ani[0], True, False)

        self.update(0)

    def update(self, pos):
        if pos != 0: 
            self.ani_speed-=1
            self.x+=pos
            if self.ani_speed == 0:
                self.img = pygame.image.load(self.ani[self.ani_pos])
                self.ani_speed = self.ani_speed_init
                if self.ani_pos == self.ani_max:
                    self.ani_pos = 0
                else:
                    self.ani_pos+=1
        screen.blit(self.img,(self.x,self.y))

h = 400
w = 800
screen = pygame.display.set_mode((w,h))
clock = pygame.time.Clock()
player1 = Player()
pos = 0

while True:
    screen.fill((0,0,0))
    clock.tick(60)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == KEYDOWN and event.key == K_RIGHT:
            pos = 1
        elif event.type == KEYUP and event.key == K_RIGHT:
            pos = 0
        elif event.type == KEYDOWN and event.key == K_LEFT:
            pos = -1
        elif event.type == KEYUP and event.key == K_LEFT:
            pos = 0

    player1.update(pos)

    pygame.display.update()