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value of `Finalize` is ever used, and it seems that the conduits that
actually manage to define it either have `()` as return type or just
throw an exception. The definition of `lift` for the `MonadTrans`
instance duplicates the base monad action there, which doesn't look
quite right to me (isn't that supposed to contain a _cleanup_
action?).

Shouldn't the constructor be changed to something like `PipeM (m (Pipe
i o m r)) (Finalize m ())` or am I completely off base here?

Thanks.

BR,
Paolo