Macro fix_enum 

macro_rules! fix_enum {
    (
        $enum_name:ident ( $tag_num:literal ) {
            $($variant:ident = $str_val:literal),* $(,)?
        }
    ) => { ... };
}

Macro for generating FIX tag enum types.

Usage example:

fix_enum! {
    Side(54) {
        Buy = "1",
        Sell = "2",
}}