Как сделать анимацию pygame

import pygame

pygame.init()

win = pygame.display.set_mode((800, 450))

pygame.display.set_caption("GAMER")

bg = pygame.image.load('bg.jpg')
playerStand = [pygame.image.load('playerStand_1.png'), pygame.image.load('playerStand_2.png'),
               pygame.image.load('playerStand_3.png')]

clock = pygame.time.Clock()

walkLeft = [pygame.image.load('playerStand_1.png')]
walkRight = [pygame.image.load('playerStand_1.png')]

x = 50
y = 305.5
weight = 64
height = 110
speed = 20
isJump = False
jumpCount = 10

left = False
right = False
animCount = 0

def drawWindow():
    global animCount

    win.blit(bg, (0, 0))
    if animCount + 1 >= 30:
        animCount = 0
    a = 30
    if left:
        win.blit(walkLeft[animCount // a], (x, y))
        animCount += 1
    elif right:
        win.blit(walkRight[animCount // a], (x, y))
        animCount += 1
    else:
        win.blit(playerStand[animCount // a], (x, y))
        animCount += 1

    pygame.display.update()

run = True
while run:

    clock.tick(60)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    keys = pygame.key.get_pressed()

    if keys[pygame.K_LEFT] and x > 20:
        x -= speed
        left = True
        right = False
    elif keys[pygame.K_RIGHT] and x < 800 - weight - 20:
        x += speed
    else:
        left = False
        right = False
        animCount = 0

    if not (isJump):
        if keys[pygame.K_SPACE]:
            isJump = True
    else:
        if jumpCount >= -10:
            if jumpCount < 0:
                y += (jumpCount ** 2) / 2
                jumpCount -= 1
            else:
                y -= (jumpCount ** 2) / 2
                jumpCount -= 1
        else:
            isJump = False
            jumpCount = 10
    drawWindow()

pygame.quit()

playerStand там я хотела сделать анимацию того как стоит перс, но включается только первая картинка. Если можно то объясните, позязя (シ_ _)シ