def generate_route(self, route):
        """Output a route definition."""
        self.emit('')
        self.emit('route %s (%s, %s, %s)' % (
            route.name,
            self.format_data_type(route.arg_data_type),
            self.format_data_type(route.result_data_type),
            self.format_data_type(route.error_data_type)
        ))
        # Output the docstring.
        with self.indent():
            if route.doc is not None:
                self.emit(self.format_string(route.doc))
Output a route definition.