If one of the walls has at least one rectangular picture hanging from it.
return walls ;return pictures ;return #2 that are  rectangular ;return #3 hanging from  #1 ;return number of #4 for each #1 ;return #1 where #5 is  at least one  ;return number of #6 ;return if  #7 is  equal to one
['select', 'select', 'filter', 'filter', 'group', 'comparative', 'aggregate', 'boolean']