static void Main(string[] args)
{
var caller = new Caller();
var result1 = caller.CallOp1(10, 5);
Console.WriteLine("Op1 result is {0}", result1);
var result2 = caller.CallOp2(10, 5);
Console.WriteLine("Op2 result is {0}", result2);
var result3 = caller.CallOp3(10, 5);
Console.WriteLine("Op3 result is {0}", result3);
}