Python newbie question: I try to wrap the xBee connection into a class. But the callback gets never called if it is a class method. If it is not in a class it works fine. What can I do?

class Receiver:
def enter(self):
self.serial_port = serial.Serial('/dev/ttyUSB0', 115200)
self.xbee = ZigBee(self.serial_port, escaped=True, callback=self.handlePackets)
Logger.info('Receiver: enter')
return self
def exit(self ,type, value, traceback):
Logger.info('Receiver: exit')
self.serial_port.close()
def handlePackets(data):
Logger.info('Receiver: packet incoming')