ModuleNotFoundError: No module named 'apache_beam', when specific languages.
Maybe the reshuffle step can be added only if the runner is not a DirectRunner ?
```py
import datasets
wiki = datasets.load_dataset('wikipedia', '20200501.ja', cache_dir='./datasets')
```
then `ModuleNotFoundError: No module named 'apache_beam'` happend.

The error doesn't appear when it's '20200501.en'.
I don't know Apache Beam, but according to #498 it isn't necessary when it's saved to local. is it correct?
ModuleNotFoundError: No module named 'apache_beam', when specific languages. 
 ```py
import datasets
wiki = datasets.load_dataset('wikipedia', '20200501.ja', cache_dir='./datasets')
```
then `ModuleNotFoundError: No module named 'apache_beam'` happend.

The error doesn't appear when it's '20200501.en'.
I don't know Apache Beam, but according to #498 it isn't necessary when it's saved to local. is it correct? 
 Maybe the reshuffle step can be added only if the runner is not a DirectRunner ?