 	# @param [Function] Callback function
 	#
 	mpset: (arr, cb) ->
-		return cb new Error "No 2D array" unless Array.isArray arr
-		return cb new Error "No 2D array" if arr.length and not Array.isArray arr[0]
-		async.each arr, ((a, cb) => @pset a[0], a[1], cb), cb
+		return cb? new Error "No 2D array" unless Array.isArray arr
+		return cb? new Error "No 2D array" if arr.length and not Array.isArray arr[0]
+		async.each arr, ((a, cb) => @pset a[0], a[1], cb), (error) ->
+			cb? error
 
 	# Get a value by key
 	#

		p = @_cleanPath p
		@client.set p, JSON.stringify(data), (error, result) ->
			log.debug "#{@id}: set", p, result
			return cb error if error
			cb()

	# Set array of persistant key-values
	#

	# @property [Object] Subscription registry
	subscriptions:    null

	# Constructor
	#
	# @param options [Object] Main options
