sub split_by_colon {
  my $string=shift;
  my @parts;
  while (length $string) {
    push @parts,"" unless @parts;
    my $char=substr($string,0,1,"");
    unless ($char eq ":") {
      $parts[-1].=$char;
    } else {
      push @parts,"";
    }
  }
  return @parts;
}