anchor.diff:  	    fWriteData.deq;
   	    return fWriteData.first.data;
   	endmethod
  +        method Bit#(idWidth) writeWid();
  +            return fWriteData.first.id;
  +        endmethod
   	method Bit#(busWidthBytes) writeDataByteEnable();
   	    return fWriteData.first.byteEnable;
   	endmethod
  
positive.code:    method Bit#(1) writeId();
  
     method ActionValue#(Bit#(busWidth)) writeData();
     method Bit#(busWidthBytes) writeDataByteEnable();
     method Bit#(1) writeLastDataBeat(); // last data beat
     method Action writeResponse(Bit#(2) responseCode, Bit#(1) id);
  
negative.code:        endmethod
  
         method ActionValue#(Bit#(busWidth)) writeData();
             return 0;
         endmethod
         method Bit#(idWidth) writeWid();
             return 0;
         endmethod
         method Bit#(busWidthBytes) writeDataByteEnable();
  