Description:

Perl's built-in logical operators, "and", "or", "xor" and "not"
support 2-value logic. This means that they always produce a result
which is either true or false. In fact Perl sometimes returns 0 and
sometimes returns undef for false depending on the operator and the
order of the arguments. For "true" Perl generally returns the first
value that evaluated to true which turns out to be extremely useful in
practice. Given the choice Perl's built-in logical operators are to be
preferred - but when you really want pure 2-degree logic or 3-degree
logic or multi-degree logic they are available through this module.