macro_rules! lazy_meta {
($enum_type:ident, $return_type:ty, $storage:ident;
$($enum_variant:ident, $return_expr:expr);*
) => { ... };
($enum_type:ident, $return_type:ty, $storage:ident;
$($enum_variant:ident, $return_expr:expr);+ ;
) => { ... };
}