code: def forward(
      self, input: torch.Tensor, lengths: torch.Tensor
  ) -> Tuple[torch.Tensor, torch.Tensor]:
      pass
  
imports: from abc import ABC, abstractmethod
  from typing import List, Optional, Tuple
  import torch
  from torchaudio.models import Emformer
label_desc: Use image node_id 1 for calling the _Transcriber obj's underlying member method code with example usage: obj.forward(input, lengths) without return types