{"ast_node_type":"other","tokens":[{"end":76,"kind":"keyword","start":0,"text":"self.universal_regions().unnormalized_input_tys[argument_index],"}]}
            self.universal_regions().unnormalized_input_tys[argument_index],
            "get_argument_index_for_region: found {fr:?} in argument {argument_index} which has type {:?}",
        );