code: def _get_algorithm(self, algorithm_name):
          
          try:
              algorithm = anomaly_detector_algorithms[algorithm_name]
              return algorithm
          except KeyError:
              raise exceptions.AlgorithmNotFound('luminol.AnomalyDetector: ' + str(algorithm_name) + ' not found.')
docs: Get the specific algorithm.
          :param str algorithm_name: name of the algorithm to use(file name).
          :return: algorithm object.