Is there any kind of guarantee that given the name of a tag `T as a 
string t that

  (Obj.magic (CamlinternalOO.public_method_label t) : int)

will compute the hash code used to represent t?  Is there a better way 
to access the hash function (passing a string, not a tag)?  Of course, I 
could reimplement it myself, but I'd like something that will track any 
changes to the internal function.

I'm trying to compute hash codes in a camlp4 extension.

Jeremy.