Check usage of lopf.py subclass

[H-Wenzel]

Purpose of the improvement

Unclear if lopf.py subclass is used and working

Proposal

It needs to be checked if somebody uses the lopf subclass and if it works properly.

If so, the ToDo:
"# TODO Check if this function is still required due to new added bounds" should be adressed.

Also, tests for lopf are needed.

Arises from #95