For more context, he/she is talking about this page: https://huggingface.co/transformers/training.html 11
I also got confused by this bit of the documentation, but I think this code expects datasets like the ones provided by Hugging Face’s NLP package 9.
I think they are all based on Pytorch’s Dataset Class 6, but I could be mistaken.
Try to use one of the datasets provided by their NLP package and check if it works correctly.
Hope this helps!