See Ehrmann et al. (2020, Section 5.2)
Also available at WWW: <https://aclanthology.org/2020.lrec-1.121/>

This reverts commit 44a6597e.

I received the following error when training:
https://discuss.huggingface.co/t/distributed-training-keyerror-eval-f1-in-questionansweringtrainer-taken-from-trainer-qa-py-in-examples/26308