public static function get_conversations_parameters() {
        return new external_function_parameters(
            array(
                'userid' => new external_value(PARAM_INT, 'The id of the user who we are viewing conversations for'),
                'limitfrom' => new external_value(PARAM_INT, 'The offset to start at', VALUE_DEFAULT, 0),
                'limitnum' => new external_value(PARAM_INT, 'Limit number of conversations to this', VALUE_DEFAULT, 0),
                'type' => new external_value(PARAM_INT, 'Filter by type', VALUE_DEFAULT, null),
                'favourites' => new external_value(PARAM_BOOL, 'Whether to restrict the results to contain NO favourite
                conversations (false), ONLY favourite conversation (true), or ignore any restriction altogether (null)',
                    VALUE_DEFAULT, null),
                'mergeself' => new external_value(PARAM_BOOL, 'Whether to include self-conversations (true) or ONLY private
                    conversations (false) when private conversations are requested.',
                    VALUE_DEFAULT, false),
            )
        );
    }