code: def is_correct(self):
          
          state = True
          for daterange in self.dateranges:
              good = daterange.is_correct()
              if not good:
                  self.add_error("[timeperiod::%s] invalid daterange '%s'"
                                 % (self.get_name(), daterange))
              state &= good
  
          # Warn about non correct entries
          for entry in self.invalid_entries:
              self.add_error("[timeperiod::%s] invalid entry '%s'" % (self.get_name(), entry))
  
          return super(Timeperiod, self).is_correct() and state
docs: Check if this object configuration is correct ::
  
          * Check if dateranges of timeperiod are valid
          * Call our parent class is_correct checker
  
          :return: True if the configuration is correct, otherwise False if at least one daterange
          is not correct
          :rtype: bool