use strict;
use warnings;

use Pod::Usage;

my $format = {
    abc => 1,
    bar => 1,
    fii => 1,
    wee => 1,
};

my $opts;
$opts->{params} = ["a", "fa"];

my $str = "(".join('|', @{$opts->{params}}).")";
if (!grep { /^$str/i } keys %$format)
{
  pod2usage( -verbose => 0, -output => \*STDERR,
          -msg => "$0 bad parameter difinition used [" . join(", ", sort {$a cmp $b} @{$opts->{params}}) . "].\n" .
                  "Possible parameters are: " . 
                  join(", ", sort {$a cmp $b} keys %$format) . "\n");
}

print "1\n";