public function determiner(string $determiner = '') : self
    {
        $enum = [
            'a', 
            'an', 
            'the',
            'auto',
            ''
        ];

        if ($this->validate and ! in_array($determiner, $enum)) {
            throw new Exception("Open Graph: Invalid determiner '{$determiner}' (unkown value)");
        }

        $this->tags[] = $this->createTag('determiner', $determiner);

        return $this;
    }