What is the membership card held by both members living in Hartford and ones living in Waterbury address?
SELECT membership_card FROM member WHERE address  =  'Hartford' INTERSECT SELECT membership_card FROM member WHERE address  =  'Waterbury'
SELECT membership_card FROM member WHERE address  =  'Hartford' INTERSECT SELECT membership_card FROM member WHERE address  =  'Waterbury'
[{'Membership_card': 'Black'}]