public INDArray output(INDArray input, boolean train, INDArray featuresMask, INDArray labelsMask) {
        return output(input, train, featuresMask, labelsMask, null);
    }
public INDArray output ( INDArray input , boolean train , INDArray featuresMask , INDArray labelsMask ) { return output ( input , train , featuresMask , labelsMask , null ) ; }
Calculate the output of the network, with masking arrays. The masking arrays are used in situations such
as one-to-many and many-to-one recurrent neural network (RNN) designs, as well as for supporting time series
of varying lengths within the same minibatch.