If there are 2 pencil cases, each with 1 zipper.
return pencil cases ;return zipper of #1 ;return number of  #2 for each  #1 ;return #1 where  #2 is equal to  one ;return number of  #4 ;return if  #5 is equal to  two
['select', 'project', 'group', 'comparative', 'aggregate', 'boolean']