public function add($name, $value)
    {
        $name      = $this->normalizeName($name);
        $newValues = is_array($value) ? $value : [$value];
        $data      = [];
        if (isset($this->data[$name])) {
            $data = $this->data[$name];
        }

        $this->data[$name] = array_merge($data, $newValues);
    }