fn cmp(&self, other: &Self) -> Ordering {
        match (self, other) {
            (A, A) | (B, B) | (C, C) => Equal,
            (A, B) | (B, C) | (C, A) => Less,
            (A, C) | (B, A) | (C, B) => Greater,
        }
    }
Looks up a given key in a (sub)tree headed by the node, rec
benchmarks/haystacks/code/rust-library.rs