AWS Cognito User Migration Lambda in Python

We've been tasked with switching our login system from an in-app system to something leveraging AWS Cognito. Doing so requires a migration step which, when done fully through AWS requires some hoops (including an AWS Lambda where the example provided from AWS is a NodeJS Lambda (where we prefer Python Lambdas) so I spent some time rewriting it and thought I'd share for those that are interested.

Finding the source of a feed

I've been concerned for a while that Feedburner was going away; with Reader's disappearance, Feedburner seems like the next obvious choice to be put out to pasture. I needed to make sure that the feeds publishing aren't using Feedburner (I fixed that a while back), but also that the feeds I'm reading (that are currently pointing to Feedburner) are pointing to the right location.