code: def end_date(self, value):
          
  
          if not isinstance(value, datetime):
              raise TypeError(_pretty_message(
                  '''
                  end_date must be an instance of datetime.datetime, not %s
                  ''',
                  _type_name(value)
              ))
  
          self._end_date = value
docs: A datetime.datetime object of when the certificate is last to be
          considered valid.