{"ast_node_type":"impl","tokens":[{"end":62,"kind":"keyword","start":0,"text":"impl"}]}
impl chalk_ir::zip::Zipper<Interner> for UnknownMismatch<'_> {
struct UnknownMismatch<'db>(&'db dyn HirDatabase);
    fn zip_tys(&mut self, variance: Variance, a: &Ty, b: &Ty) -> chalk_ir::Fallible<()> {