In the [tcomment](https://www.vim.org/scripts/script.php?script_id=1173) plugin, specifically in:

* [`~/.vim/pack/tml/start/tcomment.vim/autoload/tcomment.vim`](https://github.com/tomtom/tcomment_vim/blob/master/autoload/tcomment.vim) and
* [`~/.vim/pack/tml/start/tcomment.vim/plugin/tcomment.vim`](https://github.com/tomtom/tcomment_vim/blob/master/plugin/tcomment.vim)

I'm seeing this at the end of some lines:

```
"{{{2

```

or

```
"{{{3

```

For example:

```
let g:tcomment#blank_lines = 2    "{{{2

```

Are these some sort of special comments? Or what?

Thanks.