The contract now has two major differences:
- It raises an error when it would have to wrap.
- It uses chaperones to delay errors as long as possible
In general, using `Any` as a type when exporting to untyped
code will now just work, unless the untyped code tries to
communicate values back to the typed side, in which case an
immediate error will be raised.
Much of the implementation comes from the membrane design
from [Strickland et al, OOPSLA 2012].
962f2472e1