bug: show return type without needing to run code

[jimniels]

When you open a code cell you haven't run before, it doesn't tell you what is being returned

You have to actually run the code to see what is being returned

This seems counterintuitive. We should always show the return type, even if you haven't run the code. So any cell you open it would tell you what's being returned without you having to run the code first (especially useful for people who have read-only access to the document)