fixed

Author: dongasai

src/Input/Parser.php

@@ -247,25 +247,15 @@ protected function register(Parameter $param)
 
         $this->set($name, $param->default());
     }
-    
+
     /**
      * unRegister a new argument/option.
-     * 
+     *
      * @param string $name
      */
     public function unRegister($name)
     {
-        if (isset($this->_values[$name])) {
-            unset($this->_values[$name]);
-        }
-
-        if (isset($this->_arguments[$name])) {
-            unset($this->_arguments[$name]);
-        }
-
-        if (isset($this->_options[$name])) {
-            unset($this->_options[$name]);
-        }
+        unset($this->_values[$name], $this->_arguments[$name], $this->_options[$name]);
 
         return $this;
     }