code: def get_segment_labels(self, src_tokens):
      segment_boundary = (src_tokens == self.separator_token).long()
      segment_labels = (
          segment_boundary.cumsum(dim=1)
          - segment_boundary
          - (src_tokens == self.padding_idx).long()
      )
  
      return segment_labels
  
imports: from dataclasses import dataclass, field
  import os
  import torch
  import torch.nn
  from fairseq import utils
  from fairseq.dataclass import ChoiceEnum, FairseqDataclass
  from fairseq.models import BaseFairseqModel, register_model
  from fairseq.models.roberta.model import RobertaClassificationHead
  from fairseq.modules import LayerNorm, TransformerSentenceEncoder, TransformerSentenceEncoderLayer
label_desc: Use image node_id 3 for calling the BaseRanker obj's underlying member method code with example usage: obj.get_segment_labels(src_tokens) and returns: segment_labels