Demo how partial responses don't work so well

Hey @fwbrasil, this isn't something I want to commit, but just an example to show how I think partial responses don't work very well at the moment with the option-powered clumps. Currently there doesn't seem to be an easy way to allow "partial responses". For example, you get a tweet, then you want to get the user for the tweet. If the user cannot be found, currently you lose both the user AND the tweet. Ideally it would be better if you could make the User an option, as in the second half of the spec.

Let me know if you don't get what I mean
pretty sure I did the right thing here but I'm still a bit confused about the way the new execution model works, @fwbrasil can you doublecheck this for me?