For most ordinary keys, the "keysym" is the same as the
        corresponding ASCII value.  Other common keys are shown in the
        KEY_ constants.

def send_KeyEvent(self, key, down):
        """For most ordinary keys, the "keysym" is the same as the
        corresponding ASCII value.  Other common keys are shown in the
        KEY_ constants.
        """
        self.sendMessage(struct.pack('!BBxxI', 4, down, key))