package test.test;
public class Base {
    public static void main(String[] args) {
        Interface1 a = n -> System.out.println(2*n);
    }
}
interface Interface1 {
    void multiplyByTwo(int x);
}

package test.test;
public class Base implements Interface3 {
    public static void main(String[] args) {
        Interface3 b = n -> System.out.println(4*n);
    }
}

package test.test;
public interface Interface3 {
    void multiplyByFour(int x);
}