public function has($key)
    {
        return isset($this->override[$key]) ? true : (isset($this->data[$key]) ? true : false);
    }
public function has($key)
    {
        return isset($this->override[$key]) ? true : (isset($this->data[$key]) ? true : false);
    }
public function has ( $ key ) { return isset ( $ this -> override [ $ key ] ) ? true : ( isset ( $ this -> data [ $ key ] ) ? true : false ) ; }
Check data existence
@param string $key
@return boolean
Check data existence