{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":".vars_since_snapshot(vars_pre_snapshot.region_constraints_len);"}]}
            .vars_since_snapshot(vars_pre_snapshot.region_constraints_len);
            .unwrap_region_constraints()
        let type_vars = inner.type_variables().vars_since_snapshot(vars_pre_snapshot.type_var_len);