code: def init_states(self,
                      source_encoded: mx.sym.Symbol,
                      source_encoded_lengths: mx.sym.Symbol,
                      source_encoded_max_length: int) -> List[mx.sym.Symbol]:
          
          pass
docs: Returns a list of symbolic states that represent the initial states of this decoder.
          Used for inference.
  
          :param source_encoded: Encoded source. Shape: (batch_size, source_encoded_max_length, encoder_depth).
          :param source_encoded_lengths: Lengths of encoded source sequences. Shape: (batch_size,).
          :param source_encoded_max_length: Size of encoder time dimension.
          :return: List of symbolic initial states.