Hey, I am writing a model and the baseline is bert2bert for text summarization. But I want to add a specific layer above the Decoder. For example , I want to change the LMhead of Decoder by concatenating another vector.  But the DecoderModel outputs all the hidden states at once. I want to control it for step by step decoding. In other words. I want to  use the concatenated vector as the hidden state for generation and use the generated word vector for next step’s input. How can I change the model or call the interface properly ?