anchor.diff:      *   if n == 0 return 0  // fibstate1
       *   if n == 1 return 1
       *   tmp1 = fib(n-1)
  -    *   tmp2 = fib(n-2      // fibstate2
  +    *   tmp2 = fib(n-2)     // fibstate2
       *   return tmp1 + tmp2  // fibstate3
       */
  -   
   
      rule fib1 (frame.pc == FIBSTATE1);
         //$display("FIBSTATE1 %d", frame.args);
  
positive.code: 	   frame.doreturn();
  	end
       else
  	frame.docall(FIBSTATE1, FIBSTATE2, frame.args - 1, 0);
       endrule
  
  
negative.code: 
  interface FibIndication;
      method Action fibresult(Bit#(32) v);
  endinterface
  
  interface FibRequest;
  