Wrong documentation example for RoBERTa
Documentation web page: https://huggingface.co/pytorch-transformers/model_doc/roberta.html#pytorch_transformers.RobertaModel
See `Inputs -> input_ids`:
`tokens: [CLS] is this jack ##son ##ville ? [SEP][SEP] no it is not . [SEP]`  
and
`tokens: [CLS] the dog is hairy . [SEP]`  
are wrong examples. Because `RobertaTokenizer` says that its `cls_token` is `<cls>` not `[CLS]`.
Same for `sep_token`: it is `<sep>`, not `[SEP]`.

Using tokens `[CLS]` and `[SEP]` doesn't create any special token ids which causes errors when you try to use your encoded input in model. Adding the `add_special_tokens=True` to `encode` of course helps but you've added 2 extra tokens `[CLS]` and `[SEP]` to the input which are not known by model and possibly can decrease its quality.
Please change `[CLS]` and `[SEP]` to `<cls>` and `<sep>`.
Hi, thank you for the bug report. It has been [changed](https://huggingface.co/pytorch-transformers/model_doc/roberta.html).