GitLab

* added LongformerForQuestionAnswering

* add LongformerForQuestionAnswering

* fix import for LongformerForMaskedLM

* add LongformerForQuestionAnswering

* hardcoded sep_token_id

* compute attention_mask if not provided

* combine global_attention_mask with attention_mask when provided

* update example in  docstring

* add assert error messages, better attention combine

* add test for longformerForQuestionAnswering

* typo

* cast gloabl_attention_mask to long

* make style

* Update src/transformers/configuration_longformer.py

* Update src/transformers/configuration_longformer.py

* fix the code quality

* Merge branch 'longformer-for-question-answering' of https://github.com/patil-suraj/transformers

 into longformer-for-question-answering
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>