how to access original langurage?

[steve02081504]

I use this lib for codeblock rander, config as https://github.com/steve02081504/fount/blob/master/src/pages/scripts/markdownConvertor.mjs#L641

and when I wrote markdown like this:

```brainfuck
>+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.[-]
>++++++++[<++++>-] <.>+++++++++++[<++++++++>-]<-.--------.+++
.------.--------.[-]>++++++++[<++++>- ]<+.[-]++++++++++.
```

in my transformer createCodeBlockPlugin Ill got an this.options.lang == 'plaintext'
how can I get an 'brainfuck'?