code: def store(self, measurement):
          
          os.makedirs(self._getPathToMeasurementMetaDir(measurement.idAsPath), exist_ok=True)
          output = marshal(measurement, measurementFields)
          with open(self._getPathToMeasurementMetaFile(measurement.idAsPath), 'w') as outfile:
              json.dump(output, outfile)
          return output
docs: Writes the measurement metadata to disk on completion.
          :param activeMeasurement: the measurement that has completed.
          :returns the persisted metadata.