How many things in the background are a different color than the thing in the very front?
return things ;return #1 that  are in the background ;return #1 that  is  in the very front ;return color of #2 ;return color of #3 ;return #2 where #4 is  not the same as #5 ;return number of #6
['select', 'filter', 'filter', 'project', 'project', 'comparative', 'aggregate']