Doing the tutorial. Where was the attribute "choice_set" created?

Hi I do the tutorial. For the 5th time or even more. Something screws up and I start anew.
Now off to the question:

q = Question.objects.get(pk=1) #understood. Question with “ID=1” is now the variable q

>>> q.choice_set.all()
When was this choice_set created? It must be an attribute for the object Question. It is first mentioned on page 2

See Related objects reference | Django documentation | Django and Making queries | Django documentation | Django

Thank you ken the related objects reference link solved the question