use constant WISCONSIN => "WI";
use constant ILLINOIS => "IL";

my %abbrev_map = (
   WI => 'WISCONSIN',
   IL => 'ILLINOIS',
);

my %capitol_map = (
    WISCONSIN => "Madison",
    ILLINOIS  => "Springfield",
);

my $abbrev = "WI";
if ( exists $abbrev_map{$abbrev} ) {
    print "capitol = $capitol_map{$abbrev_map{$abbrev}}\n";
}