Speed up BTreeMap iteration by intertwined descend to the initial leaf edges
Speed up BTreeMap iteration by intertwined descend to the initial leaf edges

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust