add has

@@ -36,4 +36,20 @@ class Flags{
         // Session Driver
         return isset($_GET[$flag]) ? $_GET[$flag] : ($_SESSION[$flag] ? $_SESSION[$flag] : $defaultValue);
     }
+
+    /**
+     * Checks if the flag exists.
+     * 
+     * @param string $flag Name of the flag.
+     * @param bool $encrypted True, if the passed $flag is an encrypted value.
+     * @param string $driver Storage driver.
+     * 
+     * @return string
+     */
+    public static function has($flagName, $encrypted = false, $driver = 'cookie'){
+        $flagManager = new FlagManager();
+        $flag = $flagManager->getFlag($flagName, $encrypted);
+        if(!$flag) return null;
+        return $flagManager->checkFlag($flag, null) !== null;
+    }
 }
\ No newline at end of file