code: def forward(self, logit, label, semantic_weights=None):
      temp = F.log_softmax(logit, axis=1)
      loss_func = nn.NLLLoss(
          ignore_index=self.ignore_index,
          weight=paddle.to_tensor(self.weights),
      )
      loss = loss_func(temp, label)
      return loss
  
file_path: PaddleSeg/contrib/LaneSeg/losses/lane_cross_entropy_loss.py
imports: import paddle
  from paddle import nn
  import paddle.nn.functional
  from paddleseg.cvlibs import manager
label_desc: Use image node_id 2 for calling the LaneCrossEntropyLoss obj's underlying member method code with example usage: obj.forward(logit, label, semantic_weights) and returns: loss