docs: public void pretrain(DataSetIterator iter, int numEpochs) {
          if (numInputArrays != 1) {
              throw new UnsupportedOperationException(
                      "Cannot train ComputationGraph network with  multiple inputs using a DataSetIterator");
          }
  
          pretrain(ComputationGraphUtil.toMultiDataSetIterator(iter), numEpochs);
      }