Turn off syntax highlighting in Markdown code blocks (highlight.js underneath)

Question

I am doing a presentation using Marp. It automatically adds syntax coloring to blocks of code. For example this would be colored as Ruby:

```
def fun(x):
    x+1
end
```

I can force highlight.js to change the syntax highlighting like this:

```python
def fun(x):
    x+1
end
```

Is there a keyword which disables highlighting (something like none, default, code or unknown)?

Answer 1

According to this issue on GitHub it is possible and the keyword is text:

```text
def fun(x):
    x+1
end
```

Answer 2

I found only plaintext to work:

```plaintext
def fun(x):
    x+1
end
```

Source: https://highlightjs.org/static/demo/