Macro literally::bmap

macro_rules! bmap {
    ( $($key:expr => $value:expr),* $(,)?) => { ... };
}

Literally just a BTreeMap literal with keys and values into'd.

let m: BTreeMap<String, String> = bmap!{ "key" => "value" };
assert_eq!(m.get("key"), Some(&"value".to_string()))