with generative tests
with examples demonstrating performance
Performance: Details in comments, summary:
Screening note: We could use transients to improve performance of the distinct impl, except checking containment in a transient set is broken per (which is not currently in 1.7). I have a new patch and direction on that could provide a way to solve that if we want to move it back and push this further. Or we could just wait and refactor when does go in.