Числа Фибоначчи в X10

import x10.io.Console;

public class Fibonacci {

  public static def fib(n:int) {
    if (n<=2) return 1;
    
    val f1:int;
    val f2:int;
    finish {
      async { f1 = fib(n-1); }
      f2 = fib(n-2);
    }
    return f1 + f2;
  }

  public static def main(args:Array[String](1)) {
    val n = (args.size > 0) ? int.parse(args(0)) : 10;
    Console.OUT.println("Computing fib("+n+")");
    val f = fib(n);
    Console.OUT.println("fib("+n+") = "+f);
  }
}