If there are 4 bath-towels of equal size stacked on top of each other
return bath-towels ;return size of #1 ;return #1 where  #2 are equal ;return #3 that are stacked on top of each other ;return number of  #4 ;return if  #5 is equal to  4
['select', 'project', 'comparative', 'filter', 'aggregate', 'boolean']