Authenticate against yubico server

def auth(username, password):
    '''
    Authenticate against yubico server
    '''
    _cred = __get_yubico_users(username)

    client = Yubico(_cred['id'], _cred['key'])

    try:
        return client.verify(password)
    except yubico_exceptions.StatusCodeError as e:
        log.info('Unable to verify YubiKey `%s`', e)
        return False