Send a control command and buffer.  Internally calls doControl()
        class method and notify observers upon command/response events.
        Subclasses must override the doControl() class method.

        @param controlCode: command code

        @param bytes:       list of bytes to transmit

def control(self, controlCode, bytes=[]):
        """Send a control command and buffer.  Internally calls doControl()
        class method and notify observers upon command/response events.
        Subclasses must override the doControl() class method.

        @param controlCode: command code

        @param bytes:       list of bytes to transmit
        """
        Observable.setChanged(self)
        Observable.notifyObservers(self,
                                   CardConnectionEvent(
                                       'command',
                                       [controlCode, bytes]))
        data = self.doControl(controlCode, bytes)
        Observable.setChanged(self)
        Observable.notifyObservers(self,
                                   CardConnectionEvent(
                                       'response',
                                       data))
        if self.errorcheckingchain is not None:
            self.errorcheckingchain[0](data)
        return data