code: public INDArray outputSingle(boolean train, boolean clearInputs, INDArray... input){
          if (numOutputArrays != 1) {
              throw new IllegalStateException(
                      "Cannot use outputSingle with ComputationGraph that does not have exactly 1 output. nOutputs: "
                              + numOutputArrays);
          }
          return output(train, clearInputs, input)[0];
      }
docs: Identical to {@link #outputSingle(boolean, boolean, INDArray...)} but has the option of not clearing the input
  arrays (useful when later backpropagating external errors). Most users should use {@link #outputSingle(boolean, INDArray...)}
  in preference to this method.