extension EInt on (int,) {
  dynamic call(dynamic x) => x;
}

extension EIntIntCallInt on (int, int, {dynamic Function(dynamic) call}) {
  dynamic call(dynamic x) => x;
}

test<
        X1 extends (int,),
        X2 extends (int, {dynamic Function(dynamic) call}),
        X3 extends (int, int, {dynamic Function(dynamic) call}),
        X4 extends (String,)>(
    (int,) r1,
    (int, {dynamic Function(dynamic) call}) r2,
    (int, int, {dynamic Function(dynamic) call}) r3,
    (String,) r4,
    X1 x1,
    X2 x2,
    X3 x3,
    X4 x4,
    X1? x1n,
    X2? x2n,
    X3? x3n,
    X4? x4n) {}