Find the total population of the top 3 districts with the largest area.
return districts ;return areas of #1 ;return the   top 3 largest #2 ;;return #1 where #2 is  in #3 ;return the   populations of #5 ;return the   sum of #6
['select', 'project', 'aggregate', 'select', 'comparative', 'project', 'aggregate']