Not the creator, but I have been looking at the code for a bit.
It's probably the regex for an ID, which is
"UID_regex = re.compile('([0-9]){10}')" in rtfparser.py
and
"UID_regex = re.compile('([0-9]{10}(?=\/))')"in xmlparser.py
Regen id's will always have 10 numbers, while real players can...