helpful b0e937fff71dc0a5d34066bfd25310e76f284621 shows an example in
helpful.el where it's incredibly hard to line up the relevant parts
without duplication.
helpful 27373703625fdf86fe0f71500767802a28350b9f was supposed to show
sliders prioer to the 'big novel tree' point boost, but I can no
longer replicate. (big novel tree was difftastic 61446c9).
helpful 10943c3593901d6891ecf2350bc7eed4d560e146 also shows sliders
with parens.
helpful 982dd49c9c7e63fa94b56824f50dea4186081f8e shows some pretty
confusing paren handling in general, with lots of heavily changed
trees in the rx forms. The parens on concat (RHS line 818) would be
better on save-match-data (RHS line 815).
helpful e2609e4ae9e058bd8be6239681b2f22195628f28 shows another good
slider paren exmaple. Probably fixed by handling prev_novel correctly.