These are some advanced notes extending the material presented this week. Don't worry about mastering this stuff now if you're already feeling saturated. But you will need to learn these things in the near future, so tackle them as soon as you're ready.
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### More on multivalues ###
in (fst, snd, swap, dup)
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### Sections ###
OCaml and Haskell have a convenient bit of syntax for the common case where you want a function like this: