How many sides are visible on the blue cube in the center?
return cubes ;return #1 that  are blue ;return #1 that  are in the  center ;return #1 in both #2 and #3 ;return sides of #4 ;return #5 that  are visible ;return number of  #6
['select', 'filter', 'filter', 'intersection', 'project', 'filter', 'aggregate']