The author of this tool is Chris Barker -- back in 2015, I took his course on "Continuations and Natural Language" at the LSA. He's working on a lot of really cool stuff, so its fun to see him pop up here. The class was a summary of the research he had been doing at that time; the central idea was that some constructions in natural language can interact with their own continuations[0], dynamically changing their scope and arguments in much the same way that continuations in e.g. Lisp work. Here is a paper where he introduces the idea quite clearly:
https://www.cs.bham.ac.uk/~hxt/cw04/barker.pdf[0] https://en.wikipedia.org/wiki/Continuation