package FooConfig;

use strict;

[ constructor and some functions ]

sub important_func
{
 my $self = shift;
 my $arg = shift;

 my %hash =
 (
  '1' => 'red',
  '2' => 'blue',
  '3' => 'green',
 )

 return $hash{ $arg } if $hash{ $arg };
}