given ( $c ) {
    when ( 'a' ) {
        say 'a';
    }
    when ( 'b' ) {
        say 'b';
    }
    when ( $extra == 1 ) {
        when ( 'd' ) {
            say 'd';
        }
        when ( 'e' ) {
            say 'e';
        }
        continue;
    }
    when ( 'z' ) {
        say 'z';
    }
    default {
        say 'something else';
    }
}