It's more appropriate to use 'for-each' here. 'map' collects all of the
results into a list and returns that list, which is not needed here, and
is slightly less readable. Also, the second argument to 'find-files' is
optional; omitting it does what's needed more efficiently. So, in the
interest of promoting better practices, I would recommend this instead:
--8<---------------cut here---------------start------------->8---
(add-after 'unpack 'make-writable
(lambda _
(for-each make-file-writable
(find-files "."))
#t))
--8<---------------cut here---------------end--------------->8---