# Objective
`update_accessibility_nodes` is one of the most nested functions in the
entire Bevy repository, with a maximum of 9 levels of indentations. This
PR refactors it down to 3 levels of indentations, while improving
readability on other fronts. The result is a function that is actually
understandable at a first glance.
- This is a proof of concept to demonstrate that it is possible to
gradually lower the nesting limit proposed by #10896.
PS: I read AccessKit's documentation, but I don't have experience with
it. Therefore, naming of variables and subroutines may be a bit off.
PS2: I don't know if the test suite covers the functionality of this
system, but since I've spent quite some time on it and the changes were
simple, I'm pretty confident the refactor is functionally equivalent to
the original.
## Solution
I documented each change with a commit, but as a summary I did the
following to reduce nesting:
- I moved from `if-let` blocks to `let-else` statements where
appropriate to reduce rightward shift
- I extracted the closure body to a new function `update_adapter`
- I factored out parts of `update_adapter` into new functions
`queue_node_for_update` and `add_children_nodes`
**Note for reviewers:** GitHub's diff viewer is not the greatest in
showing horizontal code shifts, therefore you may want to use a
different tool like VSCode to review some commits, especially the second
one (anyway, that commit is very straightforward, despite changing many
lines).
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