code: def neg_pair_reduction(
      self, losses, loss_indices, embeddings, labels
  ):
      return self.element_reduction_helper(
          losses, loss_indices[0], labels
      )
  
file_path: pytorch-metric-learning/src/pytorch_metric_learning/reducers/class_weighted_reducer.py
imports: import torch
  from ..utils import common_functions
  from .base_reducer import BaseReducer
label_desc: Use image node_id 4 for calling the ClassWeightedReducer obj's underlying member method code with example usage: obj.neg_pair_reduction(losses, loss_indices, embeddings, labels) and returns: self