node nat() returns (o : int)
let
  o = 0 fby (o + 1);
tel

node f<<n : int>>(i : bool^n) returns (o, b : bool; nat : int)
let
  b = fold<<n>> (or) (i, false);
  automaton
    state Idle
      do o = false; nat = 0;
      unless b then Emit
    state Emit
      do o = true;
         nat = nat();
      until nat > 3 then Idle
      unless b then Emit
  end
tel

node main() returns (i1, i2, i3, o, b : bool; nat : int)
let
  i1 = false;
  i2 = false fby true fby false;
  i3 = false;
  (o, b, nat) = f<<3>>([i1, i2, i3]);
tel