fix some pep8 in words/

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Component: **combinatorics**

Author: **Frédéric Chapoton**

Branch/Commit: **[`5a339e1`](https://github.com/sagemath/sagetrac-mirror/commit/5a339e1fc56ba7b470b3aec91497ca6319b24ac9)**

Reviewer: **Matthias Koeppe**

_Issue created by migration from https://trac.sagemath.org/ticket/34640_

