 				return callback null, null if compressedUpdates[0]?.pack? # cannot pop from a pack
 				return callback null, compressedUpdates[0] or null
 
-	# only used in this module
 	deleteCompressedUpdate: (id, callback = (error) ->) ->
 		db.docHistory.remove({ _id: ObjectId(id.toString()) }, callback)
 
-	# used in UpdatesManager
 	popLastCompressedUpdate: (doc_id, callback = (error, update) ->) ->
 		MongoManager.getLastCompressedUpdate doc_id, (error, update) ->
 			return callback(error) if error?

			else
				callback null, null

	# used in UpdatesManager
	insertCompressedUpdates: (project_id, doc_id, updates, permanent, callback = (error) ->) ->
		jobs = []
		for update in updates

		if options.before?
			query["meta.end_ts"] = { $lt: options.before }

		PackManager.findProjectResults(db.docHistory, query, options.limit, callback)

	backportProjectId: (project_id, doc_id, callback = (error) ->) ->
		db.docHistory.update {
