This is a mostly verbatim extraction.
I re-phrased one line of code to work around a lint
false alarm. (Look for `preamble` in the diff.)
There are about 8 lines missing coverage here, so
the new module might be a good candidate to get
100% line coverage on.
Before this change, you would need to remove 74
edges from our dependency graph to make it
acyclic. Now it's 72.