// Parsing terminated mid-variable.
		return fmt.Errorf("invalid header configuration. Un-terminated variable expression '%s'", headerValue)
	}

	return nil
}

func isSpace(chr byte) bool {
	return chr == ' '

sub ComputeClass($) {
  my @ranges;
  my ($class) = @_;
  my $regexp = "[$class]";
  my $start = -1;
  for (my $i=0; $i<=129; $i++) {
    if ($i == 129) { $i = 256; }
    if ($i <= 128 && ($overrides{"$class:$i"} // chr($i) =~ $regexp)) {
      if ($start < 0) {
        $start = $i;
      }
    } else {
      if ($start >= 0) {
        push @ranges, [$start, $i-1];
      }
      $start = -1;
    }
  }
  return @ranges;