I'd like to add the 'http' scheme name in front of a given url string if it's missing. Otherwise, leave the url alone so I thought urlparse was the right way to do this. But whenever there's no scheme and I use get url, I get /// instead of '//' between the scheme and domain.

```
>>> t = urlparse.urlparse('www.example.com', 'http')
>>> t.geturl()
'http:///www.example.com' # three ///

```

How do I convert this url so it actually looks like:

```
'http://www.example.com' # two //

```