fn new_pillar(height: usize) -> Self {
        let mut root = Root::new();
        for _ in 0..height {
            root.push_internal_level();
        }
        root
    }
An iterator over the items of a `BTreeSet`.

This `struct` is created by the [`iter`] method on [`BTreeSet`].
See its docum
benchmarks/haystacks/code/rust-library.rs