public static interface ToneOptions.ContentLanguage
The language of the input text for the request: English or French. Regional variants are
treated as their parent language; for example, `en-US` is interpreted as `en`. The input
content must match the specified language. Do not submit content that contains both languages.
You can use different languages for **Content-Language** and **Accept-Language**. *
**`2017-09-21`:** Accepts `en` or `fr`. * **`2016-05-19`:** Accepts only `en`.