def get_schema_version(topic_name, version, host=TASR_HOST,
                       port=TASR_PORT, timeout=TIMEOUT):
    ''' GET /tasr/topic/<topic name>/version/<version>
    Retrieve a specific schema registered for the given topic name identified
    by a version (a positive integer).  Returns a RegisteredSchema object.
    '''
    url = ('http://%s:%s/tasr/topic/%s/version/%s' %
           (host, port, topic_name, version))
    return reg_schema_from_url(url, timeout=timeout,
                               err_404='No such version.')