//
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// UserDefaultsStore
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//
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// Copyright (c) 2018-Present Omar Albeik - https://github.com/omaralbeik
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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import Foundation
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/// `UserDefaultsStore` offers a convenient way to store a collection of `Codable` objects in `UserDefaults`.
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open class UserDefaultsStore<T: Codable & Identifiable> {
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/// Store's unique identifier.
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///
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/// **Warning**: Never use the same identifier for two -or more- different stores.
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public let uniqueIdentifier: String
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/// JSON encoder to be used for encoding objects to be stored.
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open var encoder: JSONEncoder
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/// JSON decoder to be used to decode stored objects.
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open var decoder: JSONDecoder
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/// UserDefaults store.
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private var store: UserDefaults
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/// Initialize store with given identifier.
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///
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/// **Warning**: Never use the same identifier for two -or more- different stores.
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///
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/// - Parameter uniqueIdentifier: store's unique identifier.
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/// - Parameter encoder: JSON encoder to be used for encoding objects to be stored. _default is `JSONEncoder()`_
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/// - Parameter decoder: JSON decoder to be used to decode stored objects. _default is `JSONDecoder()`_
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required public init?(
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uniqueIdentifier: String,
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encoder: JSONEncoder = .init(),
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decoder: JSONDecoder = .init()
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) {
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guard let store = UserDefaults(suiteName: uniqueIdentifier) else { return nil }
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self.uniqueIdentifier = uniqueIdentifier
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self.encoder = encoder
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self.decoder = decoder
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self.store = store
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}
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/// Save object to store. _O(1)_
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///
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/// - Parameter object: object to save.
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/// - Throws: JSON encoding error.
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public func save(_ object: T) throws {
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let data = try encoder.encode(object)
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store.set(data, forKey: key(for: object))
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increaseCounter()
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}
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/// Save optional object (if not nil) to store. _O(1)_
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///
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/// - Parameter optionalObject: optional object to save.
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/// - Throws: JSON encoding error.
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public func save(_ optionalObject: T?) throws {
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guard let object = optionalObject else { return }
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try save(object)
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}
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/// Save array of m objects to store. _O(m)_
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///
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/// - Parameter objects: object to save.
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/// - Throws: JSON encoding error.
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public func save(_ objects: [T]) throws {
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let pairs = try objects.map({ (key: key(for: $0), data: try encoder.encode($0)) })
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for pair in pairs {
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store.set(pair.data, forKey: pair.key)
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}
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increaseCounter(by: pairs.count)
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}
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/// Get object from store by its id. _O(1)_
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///
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/// - Parameter id: object id.
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/// - Returns: optional object.
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public func object(withId id: T.ID) -> T? {
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guard let data = store.data(forKey: key(for: id)) else { return nil }
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return try? decoder.decode(T.self, from: data)
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}
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/// Get array of objects from store for array of m id values. _O(m)_
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///
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/// - Parameter ids: array of ids.
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/// - Returns: array of objects with the given ids.
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public func objects(withIds ids: [T.ID]) -> [T] {
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return ids.compactMap { object(withId: $0) }
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}
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/// Get all objects from store. _O(n)_
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///
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/// - Returns: array of all objects in store.
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public func allObjects() -> [T] {
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guard objectsCount > 0 else { return [] }
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return store.dictionaryRepresentation().keys.compactMap { key -> T? in
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guard isObjectKey(key) else { return nil }
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guard let data = store.data(forKey: key) else { return nil }
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return try? decoder.decode(T.self, from: data)
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}
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}
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/// Delete object by its id from store. _O(1)_
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///
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/// - Parameter id: object id.
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public func delete(withId id: T.ID) {
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guard hasObject(withId: id) else { return }
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store.removeObject(forKey: key(for: id))
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decreaseCounter()
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}
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/// Delete objects with ids from given m ids array. _O(m)_
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///
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/// - Parameter ids: array of ids.
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public func delete(withIds ids: [T.ID]) {
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ids.forEach { delete(withId: $0) }
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}
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/// Delete all objects in store. _O(1)_
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public func deleteAll() {
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store.removePersistentDomain(forName: uniqueIdentifier)
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}
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/// Count of all objects in store. _O(1)_
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public var objectsCount: Int {
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return store.integer(forKey: counterKey)
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}
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/// Check if store has object with given id. _O(1)_
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///
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/// - Parameter id: object id to check for.
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/// - Returns: true if the store has an object with the given id.
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public func hasObject(withId id: T.ID) -> Bool {
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return object(withId: id) != nil
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}
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/// Iterate over all objects in store. _O(n)_
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///
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/// - Parameter object: iteration block.
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public func forEach(_ object: (T) -> Void) {
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allObjects().forEach { object($0) }
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}
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}
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// MARK: - Helpers
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private extension UserDefaultsStore {
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/// Increase objects count counter.
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func increaseCounter(by count: Int = 1) {
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let currentCount = store.integer(forKey: counterKey)
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store.set(currentCount + count, forKey: counterKey)
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}
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/// Decrease objects count counter.
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func decreaseCounter(by count: Int = 1) {
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let currentCount = store.integer(forKey: counterKey)
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guard currentCount > 0 else { return }
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guard currentCount - count >= 0 else { return }
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store.set(currentCount - count, forKey: counterKey)
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}
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}
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// MARK: - Keys
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private extension UserDefaultsStore {
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/// counter key.
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var counterKey: String {
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return "\(uniqueIdentifier)-count"
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}
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/// store key for object.
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///
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/// - Parameter object: object.
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/// - Returns: UserDefaults key for given object.
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func key(for object: T) -> String {
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return "\(uniqueIdentifier)-\(object[keyPath: T.idKey])"
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}
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/// store key for object by its id.
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///
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/// - Parameter id: object id.
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/// - Returns: UserDefaults key for given id.
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func key(for id: T.ID) -> String {
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return "\(uniqueIdentifier)-\(id)"
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}
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/// Check if a UserDefaults key is an object key.
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///
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/// - Parameter key: UserDefaults key
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/// - Returns: true if the key represents an object key.
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func isObjectKey(_ key: String) -> Bool {
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return key.starts(with: "\(uniqueIdentifier)-")
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}
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}
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