batch_encode_plus set a sort parameter
# 🚀 Feature request

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When use `tokenizer.batch_encode_plus`, I hope get the sorted results, so hope have the sort parameter.
Such as: `tokenizer.batch_encode_plus(..., sorted=True)`

## Motivation

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## Your contribution

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Sorted by length?
How this helps you?<|||||>> Sorted by length?
> How this helps you?

for next lstm layer<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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