This is probably more useful as an optional method hanging off the base ``Subtest`` and ``SubSubtest``  classes.  It's not much more to ask sub/subsubtests to call (for example) ``self.clean_imgs_cntrs()``.  Perhaps also pair that with another method (for sub/subsubtests) to run during ``initialize()``:  ``self.noclean_existing_imgs_cntrs()`` :smile: