         31: migrateContentThumbnails,
         32: migrateSessionModels,
         34: migrateOldTranscriptModels,
-        37: migrateIdentifiersWithoutReplacement
+        37: migrateIdentifiersWithoutReplacement,
+        43: migrateTracks
     ]
 
     init(migration: Migration, oldVersion: UInt64) {

        }
    }

}


    private static func migrateIdentifiersWithoutReplacement(with migration: Migration, oldVersion: SchemaVersion, log: OSLog) {
        // version 37 changed identifiers to include the event name prefix (i.e. "wwdc" or "fall")
        os_log("migrateIdentifiersWithoutReplacement", log: log, type: .info)

        // add `year` to `Event` based on the event's start date
        migration.enumerateObjects(ofType: "Event") { _, event in
