# declare all aribles used by arguments or config files soon, specifying their default values:

my $arg_color = 'red';
my $arg_limit = 1024;
my $arg_config;



# use Getopt::Long to parse command line arguments: die if this goes bad 

GetOptions(
  'color=s'   => \$arg_color,
  'limit=i'     => \$arg_limit ,
  
  'configuration => \$arg_config,
) or pod2usage(-verbose => 1) && exit;


# apply eventual configuration

if ($arg_config){

   # warn about option that be ovveride and import the configuration
   ...
}

# check that all options are valid warning which one is incorrect, return false and die

&check_config or die "Options are invalid";