Session07 - html renderer

This will make one new `OneLineTag` in your file for every element in content.  I don't think that's quite right.  It's probably not worth thinking about here, but the scenario I'm imagining is something like this:

```html
<a href="someplace.html">There is a <span class="funny">styled sub-element</span> in here</a>
```
You can see how in such a case, despite the nature of the `a` tag as a `OneLineTag` subclass, it should still be able to contain both text content *and* sub-elements.  

I'm getting super picky here, and this obviously goes beyond what the assignment contains in strict terms, but I think you are up for looking beyond the page.