def _authn_context_decl_ref(decl_ref, authn_auth=None):
    """
    Construct the authn context with a authn context declaration reference
    :param decl_ref: The authn context declaration reference
    :param authn_auth: Authenticating Authority
    :return: An AuthnContext instance
    """
    return factory(saml.AuthnContext,
                   authn_context_decl_ref=decl_ref,
                   authenticating_authority=factory(
                       saml.AuthenticatingAuthority, text=authn_auth))
Construct the authn context with a authn context declaration reference
    :param decl_ref: The authn context declaration reference
    :param authn_auth: Authenticating Authority
    :return: An AuthnContext instance