sub append {
my $self = shift;
my @vals = @_;
  while (my $nextvalue =shift) {
    my $wurzel = $self->{val};
     my $knoten = $wurzel; 
   while (1)  {
          if (defined($knoten)) {
       if ($nextvalue < $knoten->{'zahl'}) {
              if (defined($knoten->{linksweg})) {
           $knoten = $knoten->{linksweg};
        }         else {
               $knoten = knot($nextvalue);
        last;
  }
 
    }
    else {
      if ($nextvalue >= $knoten->{'zahl'}) {
        if (defined($knoten->{'rechtsweg'})) {
          $knoten =$knoten->{'rechtsweg'};
        }     else {
              $knoten->{'rechtsweg'} = knot($nextvalue);
              $knoten = $knoten->{rechtsweg};
            last;}
       }  
         }
      }
    }
  }
}