sub datei_lesen($)
{
   # pick parameters
   my($file) = @_;

...

       # key equals the first tract
       my $key = shift @tracts;
       my $val = [@tracts];

       # push data
       # HIER die Zuweisung ersetzen
       $data{$key} = [] unless exists $data{$key};
       push(@{$data{$key}}, $val);
   }

   # close file
   close($fhIN);

   # return data reference
   return \%data;
} # datei_lesen

sub datei_schreiben($$)
{
   # pick parameters
   my($data, $file) = @_;

...

       # iterate through the data
       foreach my$key (keys %{$data})
       {
           # create line
           # HIER die Zuweisung ersetzen
           my $line = $key . '#' . join(',', map { join('#', @{$_}) } @{$data->{$key}});

           # write out line
           print $fhOUT "$line\n";
       }

   # close file
   close($fhOUT)
       or die "close failed: $!";
} # datei_schreiben

# append data
foreach my$key (keys %{$data_to_append})
{
   # check whether we can append the data
   next if !exists($full_data->{$key});

   # append data
   # HIER ein push() einfuegen
   push(@{$full_data->{$key}->[0]}, @{shift(@{$data_to_append->{$key}})});
   push(@{$full_data->{$key}}, @{$data_to_append->{$key}});
}