def unhandledCommand(command, argument):
        """
        A command was received but not understood.

        @param command: the command received.
        @type command: L{str}, a single character.
        @param argument: the argument to the received command.
        @type argument: L{str}, a single character, or None if the command that
            was unhandled does not provide an argument.
        """

        A command was received but not understood.

        @param command: the command received.
        @type command: L{str}, a single character.
        @param argument: the argument to the received command.
        @type argument: L{str}, a single character, or None if the command that
            was unhandled does not provide an argument.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/telnet.py