protected ApplicationCommand(ApplicationViewModel vm, IScheduler scheduler) : this(vm, Observable.Never <bool>(), scheduler) { }
protected ApplicationCommand(ApplicationViewModel vm, IObservable <bool> canExecuteSource, bool initialValue = true) : this(vm, canExecuteSource, Scheduler.Immediate, initialValue) { }
protected ApplicationCommand(ApplicationViewModel vm) : this(vm, Scheduler.Immediate) { }