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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 deregister_calendar(self, name):
 """ If a calendar is registered with the given name, it is de-registered. Parameters cal_name : str The name of the calendar to be deregistered. """

        self._calendars.pop(name, None)
        self._calendar_factories.pop(name, None)
        self._aliases.pop(name, None)