public function checkbox($attrs = [])
        {
            $attrs['type'] = 'checkbox';
            $attrs['value'] = 1;

            if (isset($attrs['name'])) {
                $name = $attrs['name'];

                if (isset($_REQUEST[$name]) and $_REQUEST[$name] == 1) {
                    $attrs['checked'] = true;
                }

                $hidden = $this->hidden(['name' => $name, 'value' => '0']);
            } else {
                $hidden = '';
            }

            return $hidden . $this->open('input', $attrs);
        }