Find the captain rank that has some captains in both Cutter and Armed schooner classes.
SELECT rank FROM captain WHERE CLASS  =  'Cutter' INTERSECT SELECT rank FROM captain WHERE CLASS  =  'Armed schooner'
SELECT rank FROM captain WHERE CLASS  =  'Cutter' INTERSECT SELECT rank FROM captain WHERE CLASS  =  'Armed schooner'
[{'Rank': 'Midshipman'}]