content: import torch.nn.functional as F
  
  from ..registry import LOSSES
  from .base import BaseWeightedLoss
  
  
  @LOSSES.register_module()
  class NLLLoss(BaseWeightedLoss):
      """NLL Loss.
  
      It will calculate NLL loss given cls_score and label.
      """
  
      def _forward(self, cls_score, label, **kwargs):
          """Forward function.
  
          Args:
              cls_score (torch.Tensor): The class score.
              label (torch.Tensor): The ground truth label.
              kwargs: Any keyword argument to be used to calculate nll loss.
  
          Returns:
              torch.Tensor: The returned nll loss.
          """
          loss_cls = F.nll_loss(cls_score, label, **kwargs)
          return loss_cls
  