What color is the object that is to the left of the purple sphere and behind the yellow sphere?
return the   purple sphere  ;return the   yellow sphere  ;return objects ;return #3 that  are to  the   left of #1 ;return #3 that  are behind #2 ;return #3 in  both  #4 and #5 ;return the   color of #6
['select', 'select', 'select', 'filter', 'filter', 'intersection', 'project']