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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 DbUnExportEvent(self, argin):
 """ Mark one event channel as non exported in database :param argin: name of event channel or factory to unexport :type: tango.DevString :return: none :rtype: tango.DevVoid """

        self._log.debug("In DbUnExportEvent()")
        event_name = argin[0].lower()
        self.db.unexport_event(event_name)