Macro mozjs::rooted

macro_rules! rooted {
    (in($cx:expr) let $($var:ident)+ = $init:expr) => { ... };
    (in($cx:expr) let $($var:ident)+: $type:ty = $init:expr) => { ... };
    (in($cx:expr) let $($var:ident)+: $type:ty) => { ... };
}