case SEND_DIAGNOSTIC :
stage = new SendDiagnosticStage(this);
break;
case READ_CAPACITY_10 :// use common read capacity stage
case READ_CAPACITY_16 :
stage = new ReadCapacityStage(this);
break;
case WRITE_6 :// use common write stage
case WRITE_10 :
stage = new WriteStage(this);
break;