This runs build_tools/style.fish, which runs clang-format on C++, fish_indent on fish and (new) black on python.
If anything is wrong with the formatting, we should fix the tools, but automated formatting is worth it.
Can be used to retrieve a list of parent paths, useful for searching
ancestors recursively via their absolute paths. Paths are returned from
deepest to shallowest, starting from the path passed in. Paths are not
validated for performance reasons. (Usually the input to
__fish_parent_directories would be (pwd) or (dir $file).)
