The internal helper functions have been redesign. The initial ambition
was to create small, composable functions by-value functions and have
the high-level algorithm, which is essentially (concat . map handler
[kwlist]). However, MSVC breaking and therefore poor development speed
of utility libraries mandates adjusting the approach a bit.
The major change here is the "return value" of the helper functions
being passed by-reference to all helpers, which will append the elements
they generate onto the collection.
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