+ # for the record, Jordan had proposed the following addition as a welcome hotfix to a previous version:
+ # site_pis = list(set(site_pis))
+ # this was likely due to a bug in the above logic,
+ # that had to do with enabled persons, and where the whole loop on persons
+ # could be performed twice with the same person...
+ # so hopefully we do not need to eliminate duplicates explicitly here anymore