The example Mark Brown gives is controller support. To me, this states bits of code that could apply to almost any game would be okay, but code made for a specific type of game could be an issue. As it says code must be written within the allotted time, code from previous jams would likely not be acceptable.
Don't worry about this too much. You won't be disqualified if you use code that isn't generic enough, but you will feel shame and guilt if you copy code you could have written yourself. They just want you to have fun and try something unique.