Currently, this is handled by client-script, if needed.
<raw>``` (tab) Hello world! </new> The expressions like this causes a bug. In this case, `args` in backtickCodeBlock() is not blank (but a tab character). Then the `args` will not match both of rAllOptions and rLangCaption. So `match` will be `null`. and we can't get `match` in this case. To fix it, I check whether `match` is null or not.