Multi-line code block enclosed in backticks doesn't work

[adnan360]

Just found this project. Thanks a lot for creating this.

I was trying to use code block with 3 backticks (``` ... ```) but it doesn't work.

Input:

```
echo "test code"
```

Output:

`<code></code>
echo "test code"
`<code></code>

Should output:

<code>
echo "test code"
</code>