Python coding interview challenges
I see these challenges as a great way for excellent experienced developers to weed out incompetent companies.I'm a kick-ass get-things-done full-stack web engineer.  I've never had to deal with one of these sorts of problems in my day to day work; and if I did, I'd just find an existing, tested, stable library that already handled them.A company that needs someone to solve these sorts of problems doesn't want me on their team in the first place, nor would I thrive there.  A company that just needs to build damn good web apps is losing out by using these sorts of questions in their interviews.The best interview challenge I've had (actually, it was a take-home, with discussion in the interview proper) was about designing code for re-use and extension.  It was a great indicator of the company's practical and mature approach to engineering, and of what they really wanted this hire to accomplish.