I'm working on doing some embedding work and I have a function defined 
in C, callable in ruby that has a few default parameters.  The problem 
is that I'm not sure how to tell ruby via the C API that the last 
parameters should default to nil or 0 or whatever if they're not used.

In the mean time I can't call the "short" version of the function 
because it complains about an unmatching number of parmeters.  Is there 
any way to specify default values from within C?