code: def forward(
      self, x: torch.Tensor, x_lengths: torch.Tensor = None
  ) -> Tuple[torch.Tensor, Optional[torch.Tensor]]:
      raise NotImplementedError
  
imports: from typing import Optional, Tuple
  import torch
label_desc: Use image node_id 1 for calling the AbsSpecAug obj's underlying member method code with example usage: obj.forward(x, x_lengths) without return types