import java.util.function.Function;

public class FunctionTest {
    public static void main(String[] args) {
        Function<Integer, Integer> f1 = i -> i * 4;
        System.out.println(f1.apply(3));

        Function<String, Integer> f2 = s -> s.length();
        System.out.println(f2.apply("Hello"));
    }
}
