Genna's efficient tuple lookups with some unsafe-but-not-really memory manipulation.

little_type_trick.rs

// It copies only the string headers (no more expensive than two &str copies)
// It's unsafe but only a little type trick to make the HashMap work properly with tuple keys

let owned: ManuallyDrop<(String, String)> = 
    ManuallyDrop::new(unsafe {(mem::read(my_ref.0), mem::read(my_ref.1))});