Defines 'TRUE' and 'FALSE' constants in caller's namespace. You could use
simple values like empty string or zero for false, or any non-empty and
non-zero string value as true, but the 'TRUE' and 'FALSE' constants are
It is virtually the same as:
use constant TRUE => !! 1;
use constant FALSE => !! '';
The constants exported by 'constant::boolean' are not reported by the
Test::Pod::Coverage manpage, so it is more convenient to use this module
than to define 'TRUE' and 'FALSE' constants by yourself.
The constants can be removed from class API with 'no constant::boolean'
pragma or some universal tool like the namespace::clean manpage.