Macro language_tag

macro_rules! language_tag {
    (
        $( #[$meta:meta] )*
        $pub:vis struct $name:ident {
            $( #[$language_code_meta:meta] )*
            $language_code_pub:vis $language_code_name:ident : $language_code_ty:ty,
            $( #[$country_code_meta:meta] )*
            $country_code_pub:vis $country_code_name:ident : Option<$country_code_ty:ty>,
        }
    ) => { ... };
}