Return JSON body of the datapoints.

        :return: JSON body of the datapoints.

def _json_body_(cls):
        """Return JSON body of the datapoints.

        :return: JSON body of the datapoints.
        """
        json = []
        for series_name, data in six.iteritems(cls._datapoints):
            json.append({'name': series_name,
                         'columns': cls._fields,
                         'points': [[getattr(point, k) for k in cls._fields]
                                    for point in data]
                         })
        return json