code: public static AssociativeArray sum(DataTable2D classifierClassProbabilityMatrix) {
          AssociativeArray combinedClassProbabilities = new AssociativeArray(); 
          
          for(Map.Entry<Object, AssociativeArray> entry : classifierClassProbabilityMatrix.entrySet()) {
              //Object classifier = entry.getKey();
              AssociativeArray listOfClassProbabilities = entry.getValue();
              for(Map.Entry<Object, Object> entry2 : listOfClassProbabilities.entrySet()) {
                  Object theClass = entry2.getKey();
                  Double probability = TypeInference.toDouble(entry2.getValue());
                  
                  Double previousValue = combinedClassProbabilities.getDouble(theClass);
                  if(previousValue==null) { 
                      previousValue=0.0;
                  }
                  
                  combinedClassProbabilities.put(theClass, previousValue+probability);
              }
          }
          
          return combinedClassProbabilities;
      }
docs: Combines the responses of the classifiers by using estimating the sum
  of the probabilities of their responses.
  
  @param classifierClassProbabilityMatrix
  @return