List communication options.

def options(self, request, map, *args, **kwargs):
        """List communication options."""
        options = {}
        for method, function in map.items():
            options[method] = function.__doc__

        return self._render(
            request = request,
            template = 'options',
            context = {
                'options': options
            },
            status = 200,
            headers = {
                'Allow': ', '.join(options.keys())
            }
        )