<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def main():
 """ Start the AMP server and the reactor. """

    startLogging(stdout)
    checker = InMemoryUsernamePasswordDatabaseDontUse()
    checker.addUser("testuser", "examplepass")
    realm = AdditionRealm()
    factory = CredAMPServerFactory(Portal(realm, [checker]))
    reactor.listenTCP(7805, factory)
    reactor.run()