struct User {
    init(name: String) {
        self.name = name
    }

    let name: String

    private var interests = [Interest]()
    private var following = [User]()

    mutating func addInterest(_ interest: Interest) {
        interests.append(interest)
    }

    mutating func removeInterest(_ interest: Interest) {
        interests.removeAll(where: { $0 == interest })
    }

    mutating func follow(_ target: User) {
        following.append(target)
    }

    mutating func unfollow(_ target: User) {
        following.removeAll(where: { $0 == target })
    }

    func getFollowingList() -> [User] {
        return following
    }

    func getInterestsList() -> [Interest] {
        return interests
    }
}

extension User: Equatable {
    static func == (lhs: Self, rhs: Self) -> Bool {
        return lhs.name == rhs.name
    }
}

struct Interest {
    let name: String
}

extension Interest: Equatable {
    static func == (lhs: Self, rhs: Self) -> Bool {
        return lhs.name == rhs.name
    }
}