has 'api' => (
        is          => 'ro',
        isa         => 'SomeFramework::API',
        reader      => '_get_api',
        writer      => '_set_api',
        required    => 1,
        handles     => {
            api => 'return_self'
            # ^^^ It's supposed to have some method that
            #     returns the reference to its own object
        }
    );