50   validateBackup?: (backup) => Promiseable<boolean>;
51   shouldUseBackup?: (backup) => Promiseable<boolean>;
52   restoreBackup?: (backup, ...args: Args) => Promiseable<void>;
54   backupValidationFailed?: (backup) => void;
104   readonly validateBackup: (backup: TasksRunnerBackup<BackupDataType>) => Promiseable<boolean> =
107   readonly shouldUseBackup: (backup: TasksRunnerBackup<BackupDataType>) => Promiseable<boolean> =
111     backup: TasksRunnerBackup<BackupDataType>,
117   readonly backupValidationFailed?: (backup) => void;
156     const backup = await JsonFile.readAsync<TasksRunnerBackup<BackupDataType>>(this.backupFilePath);  constant
158     if (!(await this.isBackupValid(backup))) {
159       await this.backupValidationFailed?.(backup);
162     return !this.shouldUseBackup || (await this.shouldUseBackup(backup)) ? backup : null;
168   async isBackupValid(backup: TasksRunnerBackup<BackupDataType>): Promise<boolean> {
172       Date.now() - backup.timestamp < this.backupExpirationTime &&
173       arraysCompare(backup.resolvedTasks, this.resolvedTasks, tasksComparator) &&
174       arraysCompare(backup.tasks, this.tasks, tasksComparator)
176       return (await this.validateBackup?.(backup)) ?? true;
190     const backup: TasksRunnerBackup<BackupDataType> = {  constant
197     await fs.outputFile(this.backupFilePath, JSON.stringify(backup, null, 2));
213     const backup = await this.getBackupAsync();  constant
214     const startingIndex = backup
215       ? this.resolvedTasks.findIndex((task) => task.name === backup.lastTask) + 1
218     if (backup) {
219       await this.restoreBackup(backup, ...args);