question: Show names of shops that have more than one kind of device in stock.
#1 return shops 
#2 return devices of #1 
#3 return #2 that  are in stock 
#4 return kinds of #3 
#5 return number of  #4 for each #1 
#6 return #1 where #5 is  higher than one 
#7 return names of #6