Further explanation needed

Hi all,

Big fan of functional programming. I'm glad to see ya'll trying to bring this to Python. My question / request is pretty basic, I hope. I was looking over the docs and I saw:

`result: Result[int, Any] = Success(1).map(double)`

When looking at this I was confused for a couple of reasons, since the syntax is new to me. But the biggest stumbling block was the:

`result:`

I couldn't find a clear discussion in the documentation for what `thing:` means. Can you explain this syntax before using it in the document? I am also confused about why you would set this equal to a type? It's not clear to me how or why this works from a syntax standpoint.

Hope these are fair comments and easy to resolve!