# recursion4.py
from Processing import *
window( 500, 500 )
rectMode(CENTER)

def squares( x, y, s ):
    rect(x, y, s, s)
    if s <= 20:
        return
    else:
        s2 = 0.5*s
        squares( x-s2, y-s2, s2)
        squares( x-s2, y+s2, s2)
        squares( x+s2, y-s2, s2)
        squares( x+s2, y+s2, s2)

squares( 250, 250, 200 )