Find the name of the person who has friends with age above 40 and under age 30?
return people ;return friends of  #1 ;return ages of  #2 ;return #1 where  #3 are  above 40 ;return #1 where  #3 are  under 30 ;return #1 in both #4 and #5 ;return name of  #6
['select', 'project', 'project', 'comparative', 'comparative', 'intersection', 'project']