protected function queryString($key = null, $default = null, $deep = false)
    {
        return $key === null ? $this->getQueryString()->all() : $this->getQueryString()->get($key, $default, $deep);
    }
protected function queryString($key = null, $default = null, $deep = false)
    {
        return $key === null ? $this->getQueryString()->all() : $this->getQueryString()->get($key, $default, $deep);
    }
protected function queryString ( $ key = null , $ default = null , $ deep = false ) { return $ key === null ? $ this -> getQueryString ( ) -> all ( ) : $ this -> getQueryString ( ) -> get ( $ key , $ default , $ deep ) ; }
Returns a query string parameter by name.

@param string $key     The key
@param mixed  $default The default value if the parameter key does not exist
@param bool   $deep    If true, a path like foo[bar] will find deeper items

@return string
Returns a query string parameter by name .