             guard let serviceUUID = operation.uuid
                 else { fatalError("Should have UUID specified") }
             
-            var operation = operation
-            
             // pre-allocate array
             operation.foundData.reserveCapacity(operation.foundData.count + pdu.handlesInformationList.count)
             

        discoverCharacteristics(uuid: uuid, service: service, completion: completion)
    }
    
    // MARK: - Private Methods
    
    @inline(__always)

        
        let pdu = ATTMaximumTransmissionUnitRequest(clientMTU: clientMTU)
        
        send(pdu) { [unowned self] in self.exchangeMTUResponse($0) }
    }
    
    private func discoverServices(uuid: BluetoothUUID? = nil,
