Function onOnce

onOnce(obj, eventName, listener): IHandle
Listens for an emitted event from an object and executes a callback only once before removing the listener.
Parameters
- obj: Evented
  The object to listen to.
- eventName: string
  The name of the event to listen for.
- listener: EventHandler
  The callback to execute once the event is emitted.
Returns IHandle