Create Brain teasers for Python Den

[lauracumming]

Summary
We would like to create some harder challenges for Python Den, is there also scope for random levels?

User story
_As a student
_I would like to have some challenging exercises that i can try
_so that if I can continue to challenge myself further

Outcome/deliverable
A series of levels that are hard for the students to solve

Deadline
tbc

Links
Create doc and link here

Reviewer
@SKairinos @faucomte97

People to contact
@lauracumming