[plt-scheme] FFI: Passing a char*** into C

Hi,

I'm calling into a function[1] that expects a char*** input. From
reading the FFI docs it looks like char*** might map to a _list of
strings... or perhaps a _pointer to a _list of strings?

I'm totally new to C; so writing bindings to it is also a fun, new
experience :).

Best wishes,

Grant Rettke

[1] http://www.mcs.anl.gov/research/projects/mpi/www/www3/MPI_Init.html