use constant TWO => 2;  
$x = TWO; 
print "$x ${\TWO}\n";

##</code><code>##

use constant TWO => qw( one three );
$x = TWO; 
print "$x ${\TWO}\n";

##</code><code>##

use constant TWO => qw( one three ); 
$x = TWO; 
print "$x ${\scalar TWO}\n";