Most programming languages have a native Boolean data type. Perl
does not.

Perl has a simple and well known Truth System. The following scalar
values are false:

    $false1 = undef;
    $false2 = 0;
    $false3 = 0.0;
    $false4 = '';
    $false5 = '0';

Every other scalar value is true.

This module provides basic Boolean support, by defining two special
objects: true and false.