public static function mute_conversation(int $userid, int $conversationid) : void {
        global $DB;

        $mutedconversation = new \stdClass();
        $mutedconversation->userid = $userid;
        $mutedconversation->conversationid = $conversationid;
        $mutedconversation->action = self::CONVERSATION_ACTION_MUTED;
        $mutedconversation->timecreated = time();

        $DB->insert_record('message_conversation_actions', $mutedconversation);
    }