my( $quote, $quoted );
    if(  $str =~ /(['"])/g  ) {
        my $beg= pos($str);
        $quote= $1;
        if(  $str !~ /(?<!\\)((?:\\\\)*)\Q$quote/g  ) {
            die "Unclosed quote: ", substr($str,$beg), $/;
        }
        my $end= pos($str);
        $quoted= substr( $str, $beg, $end-$beg-1 );
    }