This isn't perfect yet, but we're trying to do this incrementally, and
merge whatever we can as early as possible.
During this work, I realized that the Simplify method of the exclusive
could probably be improved, and possibly receive a better signature.
This work will have to happen later.
We'd like to pre-compute the interpolation if we can, so that we can run
this code properly... For now, we can't so it's a compile time error...
Hopefully we can remove this restriction in the future. The problem is
the string must be a constant, or it would be possible to switch it from
"%d %s" to "%s %d %d" or anything that changes the type signature.
