module mod4 {

    prefix abc;

    namespace "urn:cesnet:mod4";

    choice ch1 {

        config true;

        default ca;

        reference "test reference";

        description "test description";

        default cb; // duplicated

        case ca {

            leaf empty { type empty; }

        }

        case cb {

            container ssh {

                presence "Enable ssh.";

            }

        }

    }

}