Controller/Controller.php
protected function addFlash($message, $type = 'info')
    {
        if (!in_array($type, ['info', 'success', 'warning', 'danger'])) {
            throw new \InvalidArgumentException(sprintf('Invalid flash type "%s".', $type));
        }
        $this->getFlashBag()->add($type, $message);
    }
protected function addFlash($message, $type = 'info')
    {
        if (!in_array($type, ['info', 'success', 'warning', 'danger'])) {
            throw new \InvalidArgumentException(sprintf('Invalid flash type "%s".', $type));
        }
        $this->getFlashBag()->add($type, $message);
    }
Adds a flash message.

@param string $message
@param string $type (info|success|warning|danger)
@throws \InvalidArgumentException