The article mentions a `duct` abstraction several times but I've never heard of this nor been able to find anything relevant through some searching. Does someone have some insights on it?
For a more detailed explanation, you can look up the type definition [2] in Arvo (Urbit's Kernel) and here [3] you can find an example of how the stack looks when setting up a timer.
[1] https://urbit.org/blog/precepts-discussion/