fn attach<'a>(
node: &mut Node,
below: &mut Vec<(&'a str, &'a Cid)>,
layer: usize,
blocks: &mut BTreeMap<Cid, Vec<u8>>,
nodes: &mut BTreeMap<Cid, Node>,
)Expand description
Builds the pending run of lower keys and hangs it off the node.
It goes on the last entry if there is one and on left if there is not,
which is the same statement as “the subtree sits between the entry before
it and the entry after it”.