Macro static_json_gettext_build 

macro_rules! static_json_gettext_build {
    ( $default_key:expr; $($key:expr => $path:expr), * $(,)* ) => { ... };
}

Used for including json files into your executable binary file for building a JSONGetText instance.

#[macro_use] extern crate json_gettext;

let ctx = static_json_gettext_build!(
    "en_US";
    "en_US" => "langs/en_US.json",
    "zh_TW" => "langs/zh_TW.json",
)
.unwrap();

println!("{:?}", ctx);