Example of a thread save singleton decorator
Possible output:
thread 0 aap running
thread 1 noot running
thread 2 mies running
thread 3 teun running
thread 4 vuur running
thread 5 gijs running
thread 6 wim running
thread 7 weide running
thread 8 does running
thread 9 kip running
1 noot noot
5 gijs noot
0 aap noot
8 does noot
2 mies noot
3 teun noot
4 vuur noot
9 kip noot
6 wim noot
7 weide noot