Function spawn_queued 

pub fn spawn_queued(
    world: &mut World,
    scene_patch_instances: &mut QueryState<&ScenePatchInstance>,
    queued: Local<'_, QueuedScenes>,
    bundle_scratch: Local<'_, BundleScratch>,
    reader: Local<'_, MessageCursor<AssetEvent<ScenePatch>>>,
    list_reader: Local<'_, MessageCursor<AssetEvent<SceneListPatch>>>,
)

A system that spawns queued scenes when they are loaded.