public function textarea($name, $id, $content = '', array $attr = null)
    {
        $basic = $this->merge_attr([ 'id' => $id ], $attr);

        return $this->input($name, [ 'id'      => $id, 'type'    => 'textarea', 'content' => $content,
                'attr'    => $basic ]);
    }