Macro fl 

macro_rules! fl {
    ($message_id:literal) => { ... };
    ($message_id:literal, $($key:ident = $value:expr),* $(,)?) => { ... };
}

Looks up a Fluent message by ID using the active language loader.

Usage

// This example uses the crate-internal fl! macro.
let label = crate::fl!("startup-loading");