Support Immutable 4.0.0 (even still rc.9)

[deepj]

Support Immutable 4.0.0 (even still rc.9)

[lukasbuenger]

@deepj Sorry for the late response.

This is going to happen in the next week. I was aware of v4 coming /being out, but I wanted to use the opportunity of a version bump to somehow reintroduce the reduceWhile iterator pattern that powered the main tree walker before I got rid of generators, because.

Also, given the fact that the main iterator always used a stack to track nodes to be iterated, I kind of wanted to explore how the new Stack DS, that got introduced by v4, works in that respect.

Thanks for the heads up though, will be on it asap!

[deepj]

@lukasbuenger thanks!