BUG: Fix issue with sets in older versions of python
BUG: Fix issue with sets in older versions of python

SuperElastix/SuperElastix,SuperElastix/SuperElastix,kaspermarstal/SuperElastix,SuperElastix/SuperElastix,kaspermarstal/SuperElastix,kaspermarstal/SuperElastix,SuperElastix/SuperElastix