from transformers import RagSequenceForGeneration gives ImportError
## Environment info
<!-- You can run the command `transformers-cli env` and copy-and-paste its output below.
     Don't forget to fill out the missing fields in that output! -->
     
- `transformers` version: 3.3.1
- Platform: Linux
- Python version:3.6.3
- PyTorch version (GPU?):
- Tensorflow version (GPU?):2.3.0
- Using GPU in script?:no
- Using distributed or parallel set-up in script?:no

### Who can help
@patrickvonplaten @sgugger 

## Information

Model I am using ():

The problem arises when using:
 


## To reproduce
1.python
>> from transformers import RagSequenceForGeneration           <- RagTokenizer is imported without any errors




## Expected behavior
I shouldn't get 
ImportError: cannot import name 'RagSequenceForGeneration'


You don't have PyTorch installed in your environment. This is a PyTorch model.<|||||>Indeed , that was the problem.
The code in https://huggingface.co/transformers/model_doc/rag.html  has import torch after the "from transformers import RagSequenceForGeneration,..." statement, so I incorrectly concluded that torch is not needed for the import. Also, that RagTokenizer got imported without errors.
Thanks!
