anchor.diff:     method Action   di(Bit#(16) v);
      method Action   rden(Bit#(1) v);
      method Action   wren(Bit#(1) v);
  +   method Action   reset(Bit#(1) v);
      method Bit#(16) dataout();
      method Bit#(1)  empty();
   endinterface: FIFO18
  
positive.code:    method Action                 fifo_wren(Bit#(1) v);
     method Action                 reset(Bit#(1) v);
     method Bit#(1)                fifo_wren_sync();
     method Reset                  fifo_reset();
     method Bit#(10)               dataout();
  endinterface: Iserdesbvi
  
  
negative.code: 
      rule dfifo_ruledi;
          dfifo.di({6'b0,serbvi.dataout()});
      endrule
  
      rule wren_dfifo_rule;
          dfifo.wren(serbvi.fifo_wren_sync());
      endrule
  
  