I wonder about setting these options here. Would it be better for _list_tasks to use getattr?
At least worth an explanatory comment.

Also, this approach will break if we add a new option to the list tasks command without also adding it here. That's not necessarily a problem with this approach, but we should probably have a unit test that will catch this. Right now, if I delete one of these options the command fails, but the unit tests pass.

I've moved _list_tasks to lib (as it is now used by more functions) and changed option retrieval to getattr.

Commit 299e0cda fixes this pull-request