 	- parameter success:      a closure called when discovering succeed.
 	- parameter failure:      a closure called when discovering failed.
 	*/
-	public func discoverServices(UUIDs: [UUID]?, success: ((Response?) -> Void)?, failure: ((CuspError?) -> Void)?) {
+	func discoverServices(UUIDs: [UUID]?, success: ((Response?) -> Void)?, failure: ((CuspError?) -> Void)?) {
 		// 0. check if ble is available
 		if let error = Cusp.central.assertAvailability() {
 			failure?(error)

	- parameter success:             a closure called when discovering succeed.
	- parameter failure:             a closure called when discovering failed.
	*/
	public func discoverCharacteristics(UUIDs: [UUID]?, ofService service: Service, success: ((Response?) -> Void)?, failure: ((CuspError?) -> Void)?) {
		// 0. check if ble is available
		if let error = Cusp.central.assertAvailability() {
			failure?(error)

	- parameter success:             a closure called when discovering succeed.
	- parameter failure:             a closure called when discovering failed.
	*/
	func discoverCharacteristics(UUIDStrings: [String]?, ofService service: Service, success: ((Response?) -> Void)?, failure: ((CuspError?) -> Void)?) {
		discoverCharacteristics(UUIDs: uuidsFrom(uuidStrings: UUIDStrings), ofService: service, success: success, failure: failure)
	}

