Special Cases

     for my $row (0..2) {
       for my $column (0..2) {
         if ($squares->[$row][$column] eq "") {
           print_cell($squares, $page, $column, $row);
         } else {
           print ("<td>" . $squares->[$row][$column] . "</td>\n");
         } 
       }
       print ("</tr><tr>\n") unless $row == 2;
     }

We can avoid the special case here
The structure of the code should echo the structure of the output
In the original code, no part of the program corresponds to a single row

     for my $row (0..2) {
       print "<tr>";
       for my $column (0..2) {
         if ($squares->[$row][$column] eq "") {
           print_cell($squares, $page, $column, $row);
         } else {
           print ("<td>" . $squares->[$row][$column] . "</td>\n");
         } 
       }
       print "</tr>\n";
     }

"If the code is well-designed, it can often handle both cases the same way"