If in one image, one barber has a customer in his chair and one does not.
return barbers ;return customers ;return chair of #1 ;return #1 that has #2 in  #3 ;return #1 besides  #4 ;return images ;return number of  #4 for each  #6 ;return #6 where  #7 is equal to  one   ;return number of  #5 for each  #8 ;return #8 where  #9 is equal to  one   ;return number of  #10 ;return if  #11 is equal to  one
['select', 'select', 'project', 'filter', 'discard', 'select', 'group', 'comparative', 'group', 'comparative', 'aggregate', 'boolean']