if no treatments return an empty array
if no treatments return an empty array

HarvardEconCS/turkserver-meteor,TurkServer/turkserver-meteor,VirtualLab/turkserver-meteor,TurkServer/turkserver-meteor,TurkServer/turkserver-meteor,VirtualLab/turkserver-meteor,VirtualLab/turkserver-meteor,HarvardEconCS/turkserver-meteor,HarvardEconCS/turkserver-meteor