$self->REST_route(
    widgets => {
        GET  => { MEDIA_TYPES => [...], FUNCTION => [...] },
        POST => { ... },
    },
    some_other_runmode => {
        GET  => { ... },
        POST => { ... },
    },
);

##</code><code>##

# nothing in setup()

sub get_widget : REST( 
                         GET    => widgets,
                         TYPES  => [ 'application/xhtml+xml', 'text/html', 'text/plain' ],
                         PARAMS => [ 'product_number' ]
                     )
{
    # implementation
}