Gridea

code is:

import random

def nexter(max):
    n=1
    id=random.random()
    while n<max:
        print id
        yield n
        n=n+1
        

for a in nexter(4):
    for b in nexter(4):
        print a,b
   

result is:

0.880003860544
0.251749859401
1 1
0.251749859401
1 2
0.251749859401
1 3
0.880003860544
0.0484719374343
2 1
0.0484719374343
2 2
0.0484719374343
2 3
0.880003860544
0.851560375492
3 1
0.851560375492
3 2
0.851560375492
3 3

so we know the generator for a lives all the time and 3 generators for b were generated (and killed)