          msg = self.error_messages['invalid'] % get_readable_date_format(datetime_input_formats)
          raise ValidationError(msg)
  
      def to_native(self, value):
          if self.output_format is not None:
              return value.strftime(self.output_format)
          return value.isoformat()
  
  
  class TimeField(WritableField):
      type_name = 'TimeField'
      widget = widgets.TimeInput
 
</s> remove         if self.output_format is not None:
            return value.strftime(self.output_format)
        return value.isoformat()
 </s> add         if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format) </s> remove         if self.output_format is not None:
            return value.strftime(self.output_format)
        return value.isoformat()
 </s> add         if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format) </s> remove         datetime_input_formats = '; '.join(self.input_formats)
 </s> add         datetime_input_formats = '; '.join(self.input_formats).replace(ISO8601, 'YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ]') </s> remove         date_input_formats = '; '.join(self.input_formats)
 </s> add         date_input_formats = '; '.join(self.input_formats).replace(ISO8601, 'YYYY-MM-DD') </s> remove         time_input_formats = '; '.join(self.input_formats)
 </s> add         time_input_formats = '; '.join(self.input_formats).replace(ISO8601, 'HH:MM[:ss[.uuuuuu]]')
        if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format)
          msg = self.error_messages['invalid'] % get_readable_date_format(datetime_input_formats)
          raise ValidationError(msg)
  
      def to_native(self, value):
        if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format)
        if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format)
        if self.output_format.lower() == ISO8601:
            return value.isoformat()
        return value.strftime(self.output_format)
  
  
  class TimeField(WritableField):
      type_name = 'TimeField'
      widget = widgets.TimeInput
keep keep keep keep replace replace replace keep keep keep keep keep
 Add new ISO8601 setting + integration 
rest_framework/fields.py