So for example, if I do 

```
# Header

```

pandoc gives out `<h1 id="header">Header</h1>`. I want something like 

```
<h1 class="something" id="header">Header</h1>

```

Is there some file where I can change the html tag output in `$body$`?

Edit, I'm looking for a "natural" change (if that makes sense). So `# header` "naturally" gives back `<h1 class="classname">header</h1>`

I guess I'll look through the source code/docs for something.