155369268 17 CTA 
155369268 70 CGA
269212605 120 TTG

##</code><code>##

   while (<$fh>) {
        chomp;
        my ($key, $pos) = split /\s+/;
        if (!$positions{$key}) {
            $positions{$key} = [$pos];
        } else {
            my $ref = $positions{$key};
            push @$ref,$pos;
        }
   }