public function alterButton(MethodInvocation $invocation)
    {
        $helper = $invocation->getThis();
        list($title, $options) = array_pad($invocation->getArguments(), 2, null);
        $options = (array)$options;
        $options = $this->_addClass($helper, $options, 'btn btn-default');

        $this->_addTemplates($helper);
        $this->setProperty($invocation, 'arguments', [$title, $options]);

        return $invocation->proceed();
    }