macro_rules! static_zip {
($selected_keys : ident, 0) => { ... };
($selected_keys : ident, 1) => { ... };
($selected_keys : ident, 2) => { ... };
($selected_keys : ident, 3) => { ... };
($selected_keys : ident, 4) => { ... };
($selected_keys : ident, 5) => { ... };
($selected_keys : ident, 6) => { ... };
($selected_keys : ident, 7) => { ... };
($selected_keys : ident, 8) => { ... };
($selected_keys : ident, 9) => { ... };
($selected_keys : ident, 10) => { ... };
($selected_keys : ident, 11) => { ... };
}