data formats. The _xdr module is no longer used, since struct
supports the required IEEE floats and doubles.
(I have one doubt about not using _xdr. The struct module doesn't
handle Inf, NaN and gradual underflow correctly. If the _xdr module
does these things better, it may still have a (small) competitive
advantage. On the other hand, since not all platforms support IEEE
floating point, it's not clear that it would be a good idea to ever
transfer Inf or NaNs. Gradual underflow can be fixed in the struct
module.