code: def get_loss(self, logits: mx.sym.Symbol, labels: mx.sym.Symbol) -> mx.sym.Symbol:
          
          raise NotImplementedError()
docs: Returns loss and softmax output symbols given logits and integer-coded labels.
  
          :param logits: Shape: (batch_size * target_seq_len, target_vocab_size).
          :param labels: Shape: (batch_size * target_seq_len,).
          :return: Loss symbol.