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This change is made with queue users in mind. Since sources of this kind *know* how to (re)create themselves, they can avoid being created at all until needed. This also adds machinery to preload tracks *before* they are needed, for gapless playback on queues and so on. Queues make use of the event system to do this.
Songbird examples
These examples show more advanced use of Songbird, or how to include Songbird in bots built on other libraries, such as twilight or serenity.