it is not obvious to me here what the value of group is if no group is supplied. I guess it's nil.

I pondered on this for a while now but did not manage to come up with a better version... I thought that something like this:

```ruby
def radio(group = nil, styles = {}, &blk)
```

might be better. But there we run into trouble when just styles are supplied (I believe they would end up in group and then we had to check if group is not a Hash and.... that's not really pretty as well)

So I think it's good - but maybe these thoughts spark some idea in someone elses head.