for my $oligo_indice ( 0 .. $#{ $self->{oligo_ref} } ) {
 print "index: $oligo_indice (";
 for my $count_indice ( 0 .. $#{ $self->{count_matrix_ref} } ) {
   if( ! defined $hd_matrix[$oligo_indice][$count_indice] ){ die "problem at [$oligo_indice][$count_indice]" }
   print $hd_matrix[$oligo_indice][$count_indice].","
 }
 print "\n";
}