{"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":".fill_with_bound_vars(DebruijnIndex::INNERMOST,"}]}
                    .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
                let subst = TyBuilder::subst_for_def(db, impl_id, None)
                    .build();