LambdaTester.java

class LambdaTester {
  interface MathOperation {
    int operation(int a, int b);
  }

  public static void main(String[] args) {
    System.out.println(testLambda(
      2,
      3,
      (a, b) -> a + b
      ));
  }

  public static int testLambda(int a, int b, MathOperation op) {
    return op.operation(a, b);
  }
}