Štvorce stredovo symetrické

import tkinter
canvas = tkinter.Canvas(bg='white', width=1000, height=2000)
canvas.pack()
x0 = 100
y0 = 100
sirka0 = 140
farba1, farba2, farba3 = 'blue', 'green', 'black'
for i in range(8):
x= x0 +250
y= y0 + 200
canvas.create_rectangle(x + i * sirka0/14 , y + i * sirka0/14, x + 140 - i * sirka0/14, y + 140 - i * sirka0/14, fill = farba1)
farba1, farba2, farba3 = farba3, farba1, farba2
tkinter.mainloop()