{
  my $subset = getsubset( $data, "R2C5:R4C8" );
  print_aoa $subset;
  is_deeply $subset, [ [ 'e' .. 'h' ], [ 15, 66, 17, 18 ], [ 55, 56, 57, 58 ] ];
  $subset->[1][2] += 5;
  say "added 5 to a value";
}
say "----------";
print_aoa $data;
say "----------";
{
  my $subset = getsubset( $data, "C8:Cn" );
  print_aoa $subset;
  is_deeply $subset,
    [ [ 8 .. 10 ], [ 'h' .. 'j' ], [ 18 .. 20 ], [ 58 .. 60 ] ];
  $subset->[1][2] = 'X';
  say "substitutes X";
}