Add LCCC dataset
_The documentation is not available anymore as the PR was closed or merged._ Thank you very much for your help @albertvillanova .

I think I have fixed all the comments.

Please let me know if this PR need further modification ;) @albertvillanova Thank you very much for your kind help.
These suggestions make the code looks more pythonic.

I have commited these changes Hi ! The dataset seems to be a duplicate of https://huggingface.co/datasets/silver/lccc - next time no need to add it on github if it's already available on huggingface.co ;) > Hi ! The dataset seems to be a duplicate of https://huggingface.co/datasets/silver/lccc - next time no need to add it on github if it's already available on huggingface.co ;)

OK, sorry for the inconvenience. I have closed another two PRs since these datasets are already available on huggingface.co It's fine, thanks @silverriver for adding these datasets !
Hi, I am trying to add a new dataset lccc.
All tests are passed.