Plugin to automatically add props to code block of a specific language?

I would like to have a plugin in my blog site to automatically set lang="lzh-Hant" (classical Chinese written in Traditional Han characters) for all syntax highlighted code in programming language wenyan as it’s too verbose to tag each and every of them with Kramdown prop syntax {: lang="lzh-Hant"}. How can I implement that? It would be nice if I could modify the Kramdown::Document for every page before they are converted to HTML.

~~~wenyan
吾有一元。名之曰「空無」。
~~~
{: lang="lzh-Hant"}