macro_rules! seq_impl {
    (
        $ty:ident < T $(: $tbound1:ident $(+ $tbound2:ident)*)* $(, $typaram:ident : $bound1:ident $(+ $bound2:ident)*)* >,
        $access:ident,
        $clear:expr,
        $with_capacity:expr,
        $reserve:expr,
        $insert:expr
    ) => { ... };
}