If "what" is a number, then this will return the corresponding playlist
item's playlist hierarchy. If it is "normal" or "playlist", it will
return the normal playlist. If it is "ml" or "media library", it will
return the media library. If it is "root" it will return the full playlist.
If it is a service discovery module's name, it will return that service
discovery's playlist. If it is any other string, it won't return anything.
If "what" is a number, then this will return the corresponding playlist
item's playlist hierarchy. If it is "normal" or "playlist", it will
return the normal playlist. If it is "ml" or "media library", it will
return the media library. If it is "root" it will return the full playlist.
If it is a service discovery module's name, it will return that service
discovery's playlist. If it is any other string, it won't return anything.