if the return value is 0 or "", and value is different from it, then the behaviour is incorrect. Alternative: we do not allow write_<par> to return None, and check for it, or even validate the returned value. Change-Id: If7381dd06f7c55bdc4a80981e67f831cd8ee4136 Reviewed-on: https://forge.frm2.tum.de/review/19728 Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de> Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>