anchor.diff:  
   // internal typeclass
   typeclass HasFPrintTraceHelper#(type t);
  -    function t fprintTraceHelper(File file, Fmt callName, Maybe#(Fmt) args, t x);
  +    function t fprintTraceHelper(File file, Bool printTimestamp, Fmt callName, Maybe#(Fmt) args, t x);
   endtypeclass
   // Base case: ActionValue#(t) (This covers Action since Action = ActionValue#(void))
   instance HasFPrintTraceHelper#(ActionValue#(t)) provisos (FShow#(t));
  -    function ActionValue#(t) fprintTraceHelper(File file, Fmt callName, Maybe#(Fmt) args, ActionValue#(t) av);
  +    function ActionValue#(t) fprintTraceHelper(File file, Bool printTimestamp, Fmt callName, Maybe#(Fmt) args, ActionValue#(t) av);
           return (actionvalue
                   t x <- av;
                   Fmt printFmt = callName;
  
positive.code: // external functions
  function t fprintTrace(File file, String msg, t x)
          provisos (HasFPrintTraceHelper#(t));
      return fprintTraceHelper(file, $format(msg), tagged Invalid, x);
  endfunction
  
  function t printTrace(String msg, t x)
          provisos (HasFPrintTraceHelper#(t));
      return fprintTraceHelper(stdout, $format(msg), tagged Invalid, x);
  endfunction
  
  module [m] fprintTraceM#(File file, String msg, m#(t) mkM)(t)
          provisos (IsModule#(m, a__), HasFPrintTraceHelper#(t));
      (* hide *)
      t _m <- mkM();
      return fprintTraceHelper(file, $format(msg), tagged Invalid, _m);
  endmodule
  
  module [m] printTraceM#(String msg, m#(t) mkM)(t)
          provisos (IsModule#(m, a__), HasFPrintTraceHelper#(t));
      (* hide *)
      t _m <- mkM;
      return fprintTraceHelper(stdout, $format(msg), tagged Invalid, _m);
  endmodule
  
  endpackage
  
negative.code:                 if (typeOf(x) != typeOf(v)) begin
                      printFmt = printFmt + $format(" = ", fshow(x));
                  end
                  if (printTimestamp) begin 
                     $fdisplay(file, "(%0d) ", $time, printFmt);
                  end
                  else begin
                     $fdisplay(file, printFmt);
                  end
                  $fflush(file);
                  return x;
              endactionvalue);
  