Are all the spheres the same material?
return spheres ;return the materials of #1 ;return number of  #1 for each #2 ;return #2 where #3 is  the  highest ;return #1 where #2 is  #4 ;return number of  #5 ;return number of  #1 ;return if  #6 and #7 are equal
['select', 'project', 'group', 'comparative', 'comparative', 'aggregate', 'aggregate', 'boolean']