BERT-large finetuned on squad v2.
F1 on dev (from paper)[https://arxiv.org/pdf/1810.04805v2.pdf] is 81.9, we reach 81.58.

F1 =
```{'exact': 78.6321906847469, 'f1': 81.5816656803201, 'total': 11873, 'HasAns_exact': 73.73481781376518, 'HasAns_f1': 79.64222615088413, 'HasAns_total': 5928, 'NoAns_exact': 83.51555929352396, 'NoAns_f1': 83.51555929352396, 'NoAns_total': 5945, 'best_exact': 78.6321906847469, 'best_exact_thresh': 0.0, 'best_f1': 81.58166568032006, 'best_f1_thresh': 0.0, 'epoch': 1.59}```