how to use 'spiece.model' to create the xlnet_tokenizer
## ❓ Questions & Help
For some reason, my computer can not connect to Internet, which means I can not use the code "tokenizer = tokenizer_class.from_pretrained('xlnet-base-cased', do_lower_case = True)" to create the tokenizer.
The Piece model (spiece.model)  is used for (de)tokenization, how can I use it to create the tokenizer?
I have tried :
`
from pytorch_transformers import XLNetTokenizer
config = {
'vocab_path' :  path.sep.join([BASIC_DIR,'pretrained/pytorch_xlnet_pretrained/spiece.model'])      
        }
tokenizer = XLNetTokenizer.from_pretrained(config['vocab_path'], do_lower_case = True)
`
it doesn't work. 
First, note that you can give proxies to the `from_pretrained` method if your connection problem comes from a proxy (see the doc/docstring for an example).

You can also download the sentence piece model from our S3 bucket (see the top of the `tokenization_xlnet.py` file for the url) and save it in a folder with the name `spiece.model`, then just give this folder path to the `from_pretrained` method.<|||||>This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
