expand-into-foreign-memory query

Hi all, I am working on a project where I believe the overhead of the call to translate-into-foreign-memory is starting to be an issue & as such I'm looking into implementing expand-into-foreign-memory. Before starting on this I thought I would ask if this feature would be welcome in cffi and also if there are any fundamental reasons this would not work. So far I have been reading the source for expand-from-foreign and expand-to-foreign and it seems that expand-into-foreign-memory would be fairly similar. Also from the comments in mem-set it looks like this feature was intended at some point. As ever thankyou for the awesome work on this project and I hope I can give something back to it soon. Cheers, Baggers