Resolves #203

I think that I implemented it the way you want based on the type signature, but if I am wrong please let me know and I would be happy to fix it.

I am happy to write tests for this, but I couldn't see where this might fit in the Test folder.

Also, I am not sure how to update the documentation, I added decorated comments in the same style as the rest of the code in that file (I assume that generates haddocks).

Checklist:

HLint

• I've changed the exposed interface (add new reexports, remove reexports, rename reexported things, etc.).
  • I've updated hlint.dhall accordingly to my changes (add new rules for the new imports, remove old ones, when they are outdated, etc.).
  • I've generated the new .hlint.yaml file (see this instructions).

General

• I've updated the CHANGELOG with the short description of my latest changes.
• All new and existing tests pass.
• I keep the code style used in the files I've changed (see style-guide for more details).
• I've used the stylish-haskell file.
• My change requires the documentation updates.
  • I've updated the documentation accordingly.
• I've added the [ci skip] text to the docs-only related commit's name.