$res .= "...\n" if (scalar @same>2);
# $res .= $diff->Next(0)."/$chunk_count\n";
if ($diff->Next(0) < $chunk_count) { # not last chunk: print 2 last lines
$res .= ' '.$same[scalar @same -2]."\n" if (scalar @same>1);
$res .= ' '.$same[scalar @same -1]."\n";
$res .= "...\n" if (scalar @same>2);
# $res .= $diff->Next(0)."/$chunk_count\n";
if ($diff->Next(0) < $chunk_count) { # not last chunk: print 2 last lines
$res .= ' '.$same[scalar @same -2]."\n" if (scalar @same>1);
$res .= ' '.$same[scalar @same -1]."\n";