if __name__ == '__main__':
from Tkinter import *
x = 360
y = 160
top = y - 30
bottom = y - 30
canvas = Canvas(width = 400,height = 600,bg = 'white')
for i in range(20):
canvas.create_oval(250 - top,250 - bottom,250 + top,250 + bottom)
top -= 5
bottom += 5
canvas.pack()
mainloop()