Macro plain_enum::plain_enum_mod

macro_rules! plain_enum_mod {
    ($modname: ident, derive($($derives:ident, )*), $enumname: ident {
            $($enumvals: ident,)*
        } ) => { ... };
    ($modname: ident, $enumname: ident {
            $($enumvals: ident,)*
        } ) => { ... };
}