Show HN: A tool to easily juggle sets of environment variables

I found myself needing to make the same request repeatedly in different environments, and could not find a good tool to switch between them and (importantly) to make it easy to see what environment I'm in, and I especially could not find one that supports fish. So, I built one and thought it might be useful to others.

I've also now found it useful for other things -- basically anytime you have some environment variables that you want to temporarily set at times, and want to track whether they're set.