Update model.py

model.py

@@ -1,3 +1,5 @@
+import torch
+import torch.nn as nn
 from transformers.models.roberta.modeling_roberta import *
 
 
@@ -87,7 +89,7 @@ class MRCQuestionAnswering(RobertaPreTrainedModel):
             start_positions = start_positions.clamp(0, ignored_index)
             end_positions = end_positions.clamp(0, ignored_index)
 
-            loss_fct = CrossEntropyLoss(ignore_index=ignored_index)
+            loss_fct = nn.CrossEntropyLoss(ignore_index=ignored_index)
             start_loss = loss_fct(start_logits, start_positions)
             end_loss = loss_fct(end_logits, end_positions)
             total_loss = (start_loss + end_loss) / 2