as intended originally, returning None should be the same
as returning the new value from the argument
Change-Id: I5596d2b6f6f525efd4dc410bbe22dad6f1fb2017
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30659
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Georg Brandl <g.brandl@fz-juelich.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>