You are correct, they have not been covered yet. I've added a note in the "work in progress" section. There are also LLRB trees that would be interesting to se

You are correct, they have not been covered yet. I've added a note in the "work in progress" section. There are also LLRB trees that would be interesting to see compared within this framework. All the red-black trees are implemented as rank-balanced trees, so there is no concept of "color" exactly, but the authors do mention the left-leaning 2-3 rule and the left-leaning red-black rule -- I just haven't implemented those yet. See Pg. 5 of https://citeseerx.ist.psu.edu/document?type=pdf&doi=52330eed3864490c8bc30c3bc2f824d2ad609be0 https://citeseerx.ist.psu.edu/document?type=pdf&doi=52330eed...