NAME    Plack::Middleware::Header - modify HTTP response headersSYNOPSIS      use Plack::Builder;       my $app = sub {['200', [], ['hello']]};      builder {          enable 'Header',            set => ['X-Plack-One' => '1'],            append => ['X-Plack-Two' => '2'],            unset => ['X-Plack-Three'];          $app;      };DESCRIPTION    Plack::Middleware::HeaderAUTHOR    Masahiro ChibaLICENSE    This library is free software; you can redistribute it and/or modify it    under the same terms as Perl itself.SEE ALSO    Plack::Middleware Plack::Builder