If the paper towels in only one of the pictures are part of a stack.
return towels ;return #1 that are paper ;return stack ;return #2 that are part of #3 ;return pictures of #4 ;return the  number of  #5 ;return if  #6 is equal to  one
['select', 'filter', 'select', 'filter', 'project', 'aggregate', 'boolean']