I found it.
Actually,it was very dummie)
I typed model.hidden[0].detach() instead of model.hidden[0].detach_().
Now it works but i’m still confused.
When i print model.modules() i still cant see extra layer:
LSTMTagger(
  (word_embeddings): Embedding(9, 6)
  (lstm): LSTM(6, 9)
  (hidden2tag): Linear(in_features=9, out_features=3)
)
Embedding(9, 6)
LSTM(6, 9)
Linear(in_features=9, out_features=3)