code: def _deleteCompletedMeasurement(self, measurementId):
          
          message, count, deleted = self.deleteFrom(measurementId, self.completeMeasurements)
          if count is 0:
              message, count, deleted = self.deleteFrom(measurementId, self.failedMeasurements)
          return message, count, deleted
docs: Deletes the named measurement from the completed measurement store if it exists.
          :param measurementId:
          :return:
              String: error messages
              Integer: count of measurements deleted