sub isBalanced {
    my $text= shift;
    my $brace= @_ ? shift : "{}";
    my $start= substr( $brace, 0, length($brace)/2 );
    my $end= substr( $brace, length($brace)/2 );
    0 while $text =~ s/\Q$start\E[^\Q$brace\E]*\Q$end\E//g;
    return $text !~ /[\Q$brace\E]/;
}