 
 final class FeedlyAccountDelegate: AccountDelegate {
 	
+	/// Feedly has a sandbox API and a production API.
+	/// This property is referred to when clients need to know which environment it should be pointing to.
 	static var environment: FeedlyAPICaller.API {
 		#if DEBUG
 		// https://developer.feedly.com/v3/developer/

	private let database: SyncDatabase
	
	private weak var currentSyncAllOperation: FeedlySyncAllOperation?
	
	init(dataFolder: String, transport: Transport?, api: FeedlyAPICaller.API) {
		
		if let transport = transport {
			caller = FeedlyAPICaller(transport: transport, api: api)
			
		} else {
			

		
		let client = FeedlyAccountDelegate.oauthAuthorizationClient
		let refreshAccessToken = FeedlyRefreshAccessTokenOperation(account: account, service: self, oauthClient: client, log: log)
		operationQueue.addOperation(refreshAccessToken)
	}
	
	static func validateCredentials(transport: Transport, credentials: Credentials, endpoint: URL?, completion: @escaping (Result<Credentials?, Error>) -> Void) {
		assertionFailure("An `account` instance should enqueue an \(FeedlyRefreshAccessTokenOperation.self) instead.")
		completion(.success(credentials))
	}
}
