如何在Pygame中创建让玩家移动的函数？

import pygame
from pygame.locals import *

pygame.init()

screen = pygame.display.set_mode((800, 600))
player = pygame.image.load("player.png")
player_rect = player.get_rect()

def move_player(direction):
    if direction == "up":
        player_rect.y -= 10
    elif direction == "down":
        player_rect.y += 10
    elif direction == "left":
        player_rect.x -= 10
    elif direction == "right":
        player_rect.x += 10

running = True
while running:
    for event in pygame.event.get():
        if event.type == QUIT:
            running = False
        elif event.type == KEYDOWN:
            if event.key == K_UP:
                move_player("up")
            elif event.key == K_DOWN:
                move_player("down")
            elif event.key == K_LEFT:
                move_player("left")
            elif event.key == K_RIGHT:
                move_player("right")
    
    screen.fill((0, 0, 0))
    screen.blit(player, player_rect)
    pygame.display.flip()