public function button($value = null, array $options = [])
    {
        $options = array_merge(['class' => 'btn btn-primary'], $options);

        $inputElement = $this->form->button($value, $options);

        $wrapperOptions = $this->isHorizontal() ? ['class' => implode(' ', [$this->getLeftColumnOffsetClass(), $this->getRightColumnClass()])] : [];
        $wrapperElement = '<div' . $this->html->attributes($wrapperOptions) . '>'. $inputElement . '</div>';

        return $this->getFormGroup(null, null, $wrapperElement);
    }