Fix docstring issues
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I think I will stop pushing to this PR, so that it can me merged for today release. 

I will open another PR for further fixing docs.

Do you agree, @lhoestq ?
2021-03-18T11:15:17Z
https://github.com/huggingface/datasets/pull/2072#issuecomment-801837176
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2021-03-18T11:15:17Z
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MEMBER
Sounds good thanks !
2021-03-18T11:16:19Z
https://github.com/huggingface/datasets/pull/2072#issuecomment-801837760
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Fix docstring issues.