News_commentary Dataset Translation Pairs are of Incorrect Language Specified Pairs
Hi @anassalamah,

Could you please try with this:
```python
train_ds = load_dataset("news_commentary", lang1="ar", lang2="en", split='train[:98%]')
val_ds = load_dataset("news_commentary", lang1="ar", lang2="en", split='train[98%:]')
``` Hello @albertvillanova, 

Thanks for the suggestion. I didn't know you could do that. however, it didn't resolve the issue

![image](https://user-images.githubusercontent.com/8571003/114169966-ec819400-993a-11eb-8a67-930f9a9b2290.png)

I used load_dataset to load the news_commentary dataset for "ar-en" translation pairs but found translations from Arabic to Hindi.  

```
train_ds = load_dataset("news_commentary", "ar-en", split='train[:98%]')
val_ds = load_dataset("news_commentary", "ar-en", split='train[98%:]')

# filtering out examples that are not ar-en translations but ar-hi
val_ds = val_ds.filter(lambda example, indice: indice not in chain(range(1312,1327) ,range(1384,1399), range(1030,1042)), with_indices=True)
```

* I'm fairly new to using datasets so I might be doing something wrong