Find the name of the person who has friends with age above 40 but not under age 30?
return people ;return friends of #1 ;return ages of #2 ;return #1 where #3 is  above 40 ;return #1 where #3 is  not under 30 ;return #1 in both #4 and  #5 ;return name of #6
['select', 'project', 'project', 'comparative', 'comparative', 'intersection', 'project']