By doing so, one has to use JSONP_SETTINGS['param_name'] only later on (and not check different locations/constants for the specified param_name).
So far, there can only be one JSONP renderer. The JSONP rendering will then be triggered when a request has set the specified 'param_name'. A nice thing would be to get the 'param_name' from the pyramid.config or the renderer itself, but those are not accessible at the time when we need it.