import Foundation

func withUserDefaults<T>(_ updates: [String: Any?], _ body: () throws -> T) rethrows -> T {
    let defaults = UserDefaults.standard
    var snapshot: [String: Any?] = [:]
    for key in updates.keys {
        snapshot[key] = defaults.object(forKey: key)
    }
    for (key, value) in updates {
        if let value {
            defaults.set(value, forKey: key)
        } else {
            defaults.removeObject(forKey: key)
        }
    }
    defer {
        for (key, value) in snapshot {
            if let value {
                defaults.set(value, forKey: key)
            } else {
                defaults.removeObject(forKey: key)
            }
        }
    }
    return try body()
}