class B<X, Y> {}

class C<X, Y> {}

class D<X extends B<X, Y>, Y extends C<X, Y>> {}

class E<X extends B<X, Y>, Y extends X Function()> {}

class F<X extends X Function()> {}

main() {}
var ld = <D>[];
var le = <E>[];
var lf = <F>[];
var md = <D, D>{};
var me = <E, E>{};
var mf = <F, F>{};