<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def init_states(self, source_encoded: mx.sym.Symbol, source_encoded_lengths: mx.sym.Symbol, source_encoded_max_length: int) -> List[mx.sym.Symbol]: """ 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. """

        pass