# this assumes that $s will never be longer than $max_length
sub my_pad {
  my ($s, $max_length, $dir, $pad_char) = @_;
  $pad_char ||= ' ';
  $dir ||= 'L';

  my $pad_string = $pad_char x ($max_length - length $s);
  return $s . $pad_string if $dir eq 'R';
  return $pad_string . $s;
}