def auth_type_str(repo_type):
    """Return valid authentication type string for given cluster type

    Arguments:
        repo_type (bool): True/False, depending on wheter it is an EE cluster
            or not.

    Returns:
        String denoting valid authentication type string as used in
        WWW-Authenticate header.
    """
    if repo_type:
        return 'acsjwt'
    else:
        return 'oauthjwt'