HashLife evolve pseudo-dole

def evolve(node):
    
    if node.depth==2:
        return evolve node using GoL rules
    else:
        res1 = evolve(node.sw)
        res2 = evolve(node.se)
        res3 = evolve(node.nw)
        res4 = evolve(node.ne)
        
        res = assembleCenterNode(re1, res2, res3, res4)
        
        return res