{"ast_node_type":"impl","tokens":[{"end":82,"kind":"keyword","start":0,"text":"//"}]}
        // impl {Meta,}Sized for (T1, T2, .., Tn) where Tn: {Meta,}Sized if n >= 1
        // impl {Meta,}Sized for ()
        ty::Tuple(tys) => Ok(ty::Binder::dummy(tys.last().map_or_else(Vec::new, |ty| vec![ty]))),