fn fivedeefork<5>(x: i32) -> i32
  zero = constant(i32, 0)
  one = constant(i32, 1)
  f = fork(start, #4, #3, #2, #1, #0)
  j = join(f)
  add = add(r, one)
  r = reduce(j, zero, add)
  z = return(j, r)