[Checkins] [zopefoundation/zc.relation] 10b9f8: Small changes for better readability

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/zc.relation
  Commit: 10b9f88ab8530ab4c0eca86416a7200d84b3e5d1
      https://github.com/zopefoundation/zc.relation/commit/10b9f88ab8530ab4c0eca86416a7200d84b3e5d1
  Author: Patrick Gerken <do3cc at patrick-gerken.de>
  Date:   2012-09-21 (Fri, 21 Sep 2012)

  Changed paths:
    M src/zc/relation/catalog.py

  Log Message:
  -----------
  Small changes for better readability

- some docstrings
- some more speaking varnames
- in one case of KeyError while removing an indexed value,
  run a consistency check on the BTree. This would raise
  an AssertionError which is slightly more helpful for the user