updated for version 7.4.609 Problem: For complicated list and dict use the garbage collector can run out of stack space. Solution: Use a stack of dicts and lists to be marked, thus making it iterative instead of recursive. (Ben Fritz)

end:
2:1
2:17
2:20
3:1
3:17
3:20
5:8
5:25
5:28
6:8
6:25
6:28
8:1
8:9
8:17
8:25
8:27
9:1
9:9
9:17
9:25
9:26
9:26