code: def pre_segment(
      self,
      xs_pad: torch.Tensor,
      ilens: torch.Tensor,
  ) -> torch.Tensor:
      raise NotImplementedError
  
imports: from abc import ABC, abstractmethod
  import torch
label_desc: Use image node_id 1 for calling the AbsSegmenter obj's underlying member method code with example usage: obj.pre_segment(xs_pad, ilens) without return types