`printout`

We now have:

      sub printout {
        for my $i (0 .. $#{$chain[1]}){
          my @chars;
          for (@chain) { 
            next unless defined;
            if ($ct_scanout) {
              $_->[$i] =~ tr/01/LH/; 
            } else {
              $_->[$i] =~ tr/X/0/;
            }
            push @chars, $_->[$i];
          }
          print OUTFILE 
            $ct_scanout ? "\n(ct_so\n" : "\n(ct_si  $ct_si{tdi}\n",
            join("", @chars), "\n )";
        }
      }

We are still making two passes:
- One pass to construct @chars in the for loop
- One pass to turn it into a string in the join
If @chars were a string, we would not have to join it