{"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
        let expected_input_tys = if let Some(expected_input_tys) = expected_input_tys {
        // If there are no external expectations at the call site, just use the types from the function defn
            assert_eq!(expected_input_tys.len(), formal_input_tys.len());