code: public List<INDArray> rnnActivateUsingStoredState(INDArray input, boolean training, boolean storeLastForTBPTT) {
          return ffToLayerActivationsDetached(training, FwdPassType.RNN_ACTIVATE_WITH_STORED_STATE, storeLastForTBPTT, layers.length-1, input, mask, null, false);
      }
docs: Similar to rnnTimeStep and feedForward() methods. Difference here is that this method:<br>
  (a) like rnnTimeStep does forward pass using stored state for RNN layers, and<br>
  (b) unlike rnnTimeStep does not modify the RNN layer state<br>
  Therefore multiple calls to this method with the same input should have the same output.<br>
  Typically used during training only. Use rnnTimeStep for prediction/forward pass at test time.
  @param input Input to network
  @param training Whether training or not
  @param storeLastForTBPTT set to true if used as part of truncated BPTT training
  @return Activations for each layer (including input, as per feedforward() etc)