sub append {
   my $self = shift;
   my @vals = @_;
   my $n = shift @vals;
   while (  my $ref_wurzel )  {
   
    if ($n < $self->{val}) {
         $self->newtree($n) 
         }
       elsif ($n >= $self->{val}) { 
          $self->newtree($n) 
          } 
}          
}