Getopt::Declare is yet another command-line argument parser, one which
is specifically designed to be powerful but exceptionally easy to use.

To parse the command-line in @ARGV, one simply creates a Getopt::Declare
object, by passing Getopt::Declare::new() a specification of the various
parameters that may be encountered.

The specification is a single string, in which the syntax of each
parameter is declared, along with a description and (optionally) one or
more actions to be performed when the parameter is encountered. The
specification string may also include other usage formatting information
(such as group headings or separators) as well as standard Perl comments
(which are ignored).