{"ast_node_type":"variable","tokens":[{"end":96,"kind":"keyword","start":0,"text":"let"}]}
                    let (_, first_expected_ty) = formal_and_expected_inputs[first_expected_idx];
                    let (first_provided_ty, first_span) = provided_arg_tys[first_provided_idx];
                    let first_provided_ty_name = if !has_error_or_infer([first_provided_ty]) {