hdb => sub {
       my $input = shift;
       my $length = length $$input;
       my $i = 0;
       my $possible;
       my $j;
       while( 1 ) {
           $possible = substr $$input, 0, ++$i;
 print "i: $i : l:", length $possible;
           $possible = substr $$input, 0, $i=$j if ($j = index $$input, $possible, $i) > 0 ;
 print "i:$i j:$j : l:", length $possible;
           return $possible if substr( $$input, $i ) eq substr($$input, 0, $length - $i);
       }
    },