@staticmethod
def build_username_from_suffix(username, suffix):
    """
            Transform backend username into federated username using ``suffix``

            :param unicode username: A CAS backend returned username
            :param unicode suffix: A suffix identifying the CAS backend
            :return: The federated username: ``username`` @ ``suffix``.
            :rtype: unicode
        """
    return u'%s@%s' % (username, suffix)
