Improve params.

src/Libs/Params.php

@@ -13,6 +13,10 @@ class Params {
       }
     }
     
+    public function __isset($index) {
+      return isset($this->data[$index]);
+    }
+    
     public function __get($index){
         return (isset($this->data[$index]) && $this->data[$index] != '') ? $this->data[$index] : null;
     }