docs: public void assignSubToCenters(KDTreeNode node, Instances centers,
        int[] centList, int[] assignments) throws Exception {
      // todo: undecided situations
      int numCent = centList.length;
  
      // WARNING: assignments is "input/output-parameter"
      // should not be null and the following should not happen
      if (assignments == null) {
        assignments = new int[m_Instances.numInstances()];
        for (int i = 0; i < assignments.length; i++) {
          assignments[i] = -1;
        }
      }
  
      // set assignments for all instances of this node
      for (int i = node.m_Start; i <= node.m_End; i++) {
        int instIndex = m_InstList[i];
        Instance inst = m_Instances.instance(instIndex);
        // if (instList[i] == 664) System.out.println("664***");
        int newC = m_EuclideanDistance.closestPoint(inst, centers, centList);
        // int newC = clusterProcessedInstance(inst, centers);
        assignments[instIndex] = newC;
      }
    }