Add custom classes and extra divs inside the njk macro code

I was just wondering if there was a way to add custom `li` classes or extra `divs` for the child nav list?

So particularly for 
```
<ul>
{%- for entry in navPages %}{{ renderNavListItem(entry) }}{%- endfor -%}
</ul>
```
Is there a way to extend this, so still generating the child nav links while being able to customise the code with extra html?