Update model.py

model.py

@@ -1,8 +1,10 @@
 from transformers import BertModel, BertConfig
+from abc import ABCMeta
 from transformers.modeling_outputs import BaseModelOutputWithPooling
 import torch.nn as nn
 import torch.nn.functional as F
-from transformers import PreTrainedModel, SequenceClassifierOutput
+from transformers.modeling_outputs import SequenceClassifierOutput
+from transformers import PreTrainedModelt
 from transformers import PretrainedConfig
 
 class BertLSTMConfig(PretrainedConfig):
@@ -31,7 +33,7 @@ class BertLSTMConfig(PretrainedConfig):
         }
 
 
-class BertLSTMForSequenceClassification(PreTrainedModel):
+class BertLSTMForSequenceClassification(PreTrainedModel,, metaclass=ABCMeta):
     config_class = BertLSTMConfig
 
     def __init__(self, config):