Macro command_enum

macro_rules! command_enum {
    (
        $(#[$doc:meta])*
        $cmd:ident {
            default: $default_cmd:ident ($default_cmd_ty:expr),
            $(
                $(#[$doc_var:meta])*
                $cmd_var:ident ($cmd_mod:ident :: $cmd_inner:ident),
            )+
        }
    ) => { ... };
}

Convenience macro to define a wrapper enum around command class variants.