files, we only need to call bootstrap functions after all.
(So we may not even need to parse the rust code, rather, just provide a list
of perl packages to create...)
-* Add prototypes to exported functions.
-* Allow "trailing" `Option` parameters to be skipped in perl.
- eg. `fn foo(x: u32, y: Option<u32>);` should be callable as `foo(1)`, rather than requiring
- `foo(1, undef)`.
Current recommended usage.
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