Z = [[0,0,0,0,0,0],
     [0,0,0,1,0,0],
     [0,1,0,1,0,0],
     [0,0,1,1,0,0],
     [0,0,0,0,0,0],
     [0,0,0,0,0,0]]

def compute_neighbours(Z):
    shape = len(Z), len(Z[0])
    N  = [[0,]*(shape[0])  for i in range(shape[1])]
    for x in range(1,shape[0]-1):
        for y in range(1,shape[1]-1):
            N[x][y] = Z[x-1][y-1]+Z[x][y-1]+Z[x+1][y-1] \
                    + Z[x-1][y]            +Z[x+1][y]   \
                    + Z[x-1][y+1]+Z[x][y+1]+Z[x+1][y+1]
    return N

def show(Z):
    for l in Z[1:-1]:
        print l[1:-1]
    print

def iterate(Z):
    shape = len(Z), len(Z[0])
    N = compute_neighbours(Z)
    for x in range(1,shape[0]-1):
        for y in range(1,shape[1]-1):
            if Z[x][y] == 1 and (N[x][y] < 2 or N[x][y] > 3):
                Z[x][y] = 0
            elif Z[x][y] == 0 and N[x][y] == 3:
                Z[x][y] = 1
    return Z

show(Z)
for i in range(4):
    iterate(Z)
show(Z)