code: def _serialize_value(self, value):
          
  
          if isinstance(value, datetime.datetime):
              return value.strftime(self.datetime_format)
          elif isinstance(value, datetime.date):
              return value.strftime(self.date_format)
          elif isinstance(value, datetime.time):
              return value.strftime(self.time_format)
          return text_type(value)
docs: Serialize values like date and time. Respect other values:
          :return: