wow, shower is really quite powerful
quick workaround for hljs' bug

it's equivalent to removing those lines:
https://github.com/isagalaev/highlight.js/blob/b26a4c6470b7c7fe554d54e7a7ee2a6d6ad675e8/src/languages/ruby.js#L124-L144

we don't really need to detect inheritance, and it's conflicting
with html inserted in the pre code block.
not really used
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