protected function setStyle($style)
    {
        if (is_string($style) === false) {
            throw new \InvalidArgumentException(
                'The style label must be a string.'
            );
        }
        if (!in_array($style, $this->STYLES)) {
            throw new \InvalidArgumentException(
                'Invalid style.'
            );
        }

        $this->style = $style;

        return $this;
    }