def requestAvatarId(self, credentials):
        username, domain = credentials.username.split("@")
        pw = self.users.get((domain, username))
        if pw is None:
            return defer.fail(UnauthorizedLogin())
        def _(passwordIsCorrect):
            if passwordIsCorrect:
                return username + '@' + domain
            else:
                raise UnauthorizedLogin()
        return defer.maybeDeferred(
            credentials.checkPassword, pw).addCallback(_)
dataset/ETHPy150Open twisted/vertex/vertex/q2q.py/DefaultCertificateStore.requestAvatarId/original