"Is next sentence" pre-training task availability for Language Modeling scripts
# 🚀 Feature request

BERT was trained on 2 pretraining tasks. The scripts [here ](https://github.com/huggingface/transformers/tree/master/examples/pytorch/language-modeling) in the repo for language modeling only provide scripts for masked language modeling.

Is there any specific reason for this?

I was hoping if those scripts could be extended to include "next sentence" pretraining task to remain faithful to the pretraining methodology used by BERT if I choose to further pretrain on some corpus.

## Motivation

BERT uses 2 pre-training tasks and the scripts provide only of them.

## Your contribution

I am not sure if I can extend the script myself. I will gladly look into them if I know the there aren't any good reasons for them not being provided by HF in the first place.

Thanks a lot!
Related issues: https://github.com/huggingface/transformers/issues/1622, https://github.com/huggingface/transformers/issues/2898 and https://github.com/huggingface/transformers/issues/2166

However, example scripts are made to be very understandable and very easy to tweak, so modifying them to include the next sentence prediction objective for BERT shouldn't be complicated! <|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.<|||||>Same issue! Anybody done it before?
Have been trying using Hugging face library for more than a month now. Still running into issues