macro_rules! construct_uint {
( $(#[$attr:meta])* $visibility:vis struct $name:ident (1); ) => { ... };
( $(#[$attr:meta])* $visibility:vis struct $name:ident ( $n_words:tt ); ) => { ... };
( @construct $(#[$attr:meta])* $visibility:vis struct $name:ident ( $n_words:tt ); ) => { ... };
}