Stash is a library for efficiently storing maps of keys to values when one
doesn't care what the keys are but wants blazing† fast
insertions, deletions, and lookups.
Common use cases include file descriptor tables, session tables, or MIO context tables.
†Blazing means an order of magnitude faster than hash maps and btree maps.
A versioned index into a
Every index type to be used with Stash needs to implement this trait