code: def deregister_calendar(self, name):
          
          self._calendars.pop(name, None)
          self._calendar_factories.pop(name, None)
          self._aliases.pop(name, None)
docs: 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.