Deprecate num_proc parameter in  DownloadManager.extract
fixes #5132 : Deprecated the `num_proc` parameter in `DownloadManager.extract` by passing `num_proc` parameter to `map_nested` .
_The documentation is not available anymore as the PR was closed or merged._ Hey @mariosasko . Can you please help me with why the tests keep failing.  I have reviewed the code changes multiple times but can't spot any mistakes.  You can fix this failure by formatting your code with the `make style` command (run it from the root of the cloned repo). hey @mariosasko ,i cant understand how to use the `make style` command .I searched for it on the internet but cant find any results. 
So i formatted the code using vs-code document formatter. Hope this helps. `make style` runs the "style" target defined here: https://github.com/huggingface/datasets/blob/f09f781be3278156ce3aa6ec90c1926b1846a78f/Makefile#L12

This seems to be a good tutorial on Makefiles: https://opensource.com/article/18/8/what-how-makefile 



> `make style` runs the "style" target defined here:
> 
> https://github.com/huggingface/datasets/blob/f09f781be3278156ce3aa6ec90c1926b1846a78f/Makefile#L12
> 
> This seems to be a good tutorial on Makefiles: https://opensource.com/article/18/8/what-how-makefile

Thanks! I will look into this :relaxed: 