suggest_people_you_may_know

import functools


def suggest_people_you_may_know(graph, user):
    friends = graph[user]
    suggestions = set()

    def reducer(acc, elem):
        friendsOfFriend = graph[elem]

        def reducer2(acc2, elem2):
            if elem2 != user and elem2 not in friends:
                suggestions.add(elem2)
        functools.reduce(reducer2, friendsOfFriend, None)

    functools.reduce(reducer, friends, None)
    return suggestions

g = {
"Ana": ["Andrei", "Bogdan", "Maria"],
"Andrei": ["Ana", "Bogdan", "Robert"],
"Bogdan": ["Ana", "Andrei"],
"Maria": ["Ana"],
"Robert": ["Andrei"]
}
print(suggest_people_you_may_know(g, "Bogdan"))