class Covariant<out T> {}
class Contravariant<in T> {}
class Invariant<inout T> {}
void covariantListInfer<T>(Covariant<List<T>> x) {}
void contravariantListInfer<T>(Contravariant<List<T>> x) {}
void invariantListInfer<T>(Invariant<List<T>> x) {}
main() {}