sub validate
{
	my $options = shift;
	$options->{-one} = 1 unless ( exists( $options->{-one} ) );
	$options->{-two} = 2 unless ( exists( $options->{-two} ) );
	
	die "Error: -one ($options->{-one}) > -two ($options->{-two}), "
	  if ( $options->{-one} > $options->{-two} );
}
$options = Getopt::Declare->new( <<'OPTIONS' );
...
OPTIONS
validate( $options );