When {HEAD ~ the cup portion} is empty of {TAIL ~ the beverage}, the user can then remove the stopper 
is empty of
When { HEAD ~ the cup portion } is empty of { TAIL ~ the beverage } , the user can then remove the stopper
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH