code: def get_cluster(self, label):
          
          for cluster in self._clusters:
              if label == cluster['label']:
                  return self._get_connection(cluster)
          raise AttributeError('No such cluster %s.' % label)
docs: Returns a connection to a mongo-clusters.
  
          Args:
              label (string): the label of a cluster.
  
          Returns:
              A connection to the cluster labeld with label.
  
          Raises:
              AttributeError: there is no cluster with the given label in the
                  config