Added bits of refactoring, and a test, removed python27 in tox

[MarkVerbeek91]

This module help me a lot during my work. So I want to return a (small) favor.

I did my best to have python27 also running, but windows was not cooperating. As python 2.7 is EOL since two years now, I think is save not to support it any more.

When appreciated I can refactor some more, and increate the test coverage. In future PRs.