{
   my $seq = HashSequences();
   SpecifySeqLengths($seq);
}

sub HashSequences {
   my $seq = {};
   ...
      $seq->{$id} .= $1;
   ...
   return $seq;
}

sub SpecifySeqLengths {
   my ($seq) = @_;
   ...
   for my $id (keys %$seq) {
      ... length($seq->{$id}) ...
   }
   ...
}