Bert Cola Example Missing Import

[jackn11]

In the example at the link below, line 36 yields the error that todevice is not defined. This is because there is no general import which includes that method such as using Transformers which includes that method in the file. This could easily be fixed by including using Transformers at the top of the file.

https://github.com/chengchingwen/Transformers.jl/blob/master/example/BERT/cola/train.jl

[chengchingwen]

Because it's not the top-level entry. Please refer to the instructions in the readme