code: def get_activation(self, cls_score):
      fine_cls_score = cls_score[:, : self.num_classes]
  
      score_classes = fine_cls_score.sigmoid()
  
      return score_classes
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from mmcv.ops import sigmoid_focal_loss
  from mmdet.registry import MODELS
  from .accuracy import accuracy
  from .utils import weight_reduce_loss
label_desc: Use image node_id 3 for calling the FocalCustomLoss obj's underlying member method code with example usage: obj.get_activation(cls_score) and returns: score_classes