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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cmd(self, command, args, prefix=None):
 """ Sends a command to the server. :param command: IRC code to send. :type command: unicode :param args: arguments to pass with the command. :type args: basestring :param prefix: optional prefix to prepend to the command. :type prefix: str or None """

        if prefix is None:
            prefix = u''
        raw_cmd = u'{0} {1} {2}'.format(prefix, command, args).strip()
        self._send(raw_cmd)