use strict;
use warnings;
use Insensitive::Hash;

tie my %hash, 'Insensitive::Hash', ( 'Content-Type' => 'text/plain' );
# <=> my $hash = Insensitive::Hash->TIEHASH( ... )

$hash{'Content-Type'}; # <=> $hash->FETCH( 'Content-Type' );
$hash{'content-type'}; # <=> $hash->FETCH( 'content-type' );

$hash{'CONTENT-TYPE'} = 'text/html';
# <=> $hash->STORE( 'CONTENT-TYPE' => 'text/html' );