If an image shows a stack of at least two solid gray towels.
return towels ;return #1 that are  solid gray ;return stack of  #2 ;return number of #2 for each #3 ;return #3 where #4 is  at least two ;return If #5 is  in  an image
['select', 'filter', 'project', 'group', 'comparative', 'boolean']