在python中使用zelle图形的动画

我需要帮助来设计我的图形,没有Turtle和Tkinter,但是有Zelle graphics.py。问题是我需要同时跑4圈。这是我目前掌握的代码:

 from graphics import *
    import time #import time module

from random import randrange
def rand_color():#generates a random color and returns that color
    return(color_rgb(randrange(256),randrange(256),randrange(256)))
def main():
    win = GraphWin("My Circle",500,500)\
    c = Circle(Point(20,20),20)
    c.setFill(rand_color())
    c.draw(win)
    for i in range(1,461):
        c.move(1,1)
        time.sleep(.005)

    c = Circle(Point(20,20),20)
    c.setFill(rand_color())
    c.draw(win)
    for i in range(1,461):
        c.move(-1,1)
        time.sleep(.005)

    c = Circle(Point(20,20),20)
    c.setFill(rand_color())
    c.draw(win)
    for i in range(1,461):
        c.move(1,-1)
        time.sleep(.005)

    c = Circle(Point(20,20),20)
    c.setFill(rand_color())
    c.draw(win)
    for i in range(1,461):
        c.move(1,1)
        time.sleep(.005)
main()

我不知道如何同时移动多个对象。怎么办?