[WIP] Complete offset prefix mapping
Checklist for PRs :

- [x] closes #7985
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @tv3141! Thanks for updating the PR.



Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on April 02, 2018 at 12:06 Hours UTC closing as stale. if you'd like to continue working, pls ping.