personaltypes.py is missing include

The documentation for debugging helpers show the usage of Children(d).

Trying to get a grasp of what is going on I was cut and pasting a lot of code, but all I got was access denied. In the end it turned out, that personaltypes.py did not import Children, which took me a good while to figure out.

My suggestion is to add

from dumper import Children

to the top of personaltypes.py