sub revcompl {
  my (@dna) = @_;
  my @dr=();
  foreach my $segment (@dna) {
    my $revcomp = reverse($segment);
    $revcomp =~ tr/ACGTacgtMKRYBDHVmkrybdhv/TGCAtgcaKMYRVHDBkmyrvhdb/;
    push  @dr, $revcomp;
  }
  $done = join('',@dr);
  return $done;
}