employees = ['Corey', 'Jim', 'Steven', 'April', 'Judy', 'Jenn', 'John', 'Jane']

gym_members = ['April', 'John', 'Corey']

developers = ['Judy', 'Corey', 'Steven', 'Jane', 'April']

if 'Corey' in developers:
    print('Found!')

# O(n) for list
# O(1) for a set