    "Given a function with two parameter lists, return a
     function with the order of the argument lists reversed. The
     parameter lists may have any number of parameters.

     That is, if `fun` has type `W(A,B)(X,Y,Z)` then
     `shuffle(fun)` has type `W(X,Y,Z)(A,B)`.

     This function is often used in conjunction with `curry()`."
    see (`function curry`)
    tagged("Functions")
    shared Result(*FirstArgs)(*SecondArgs)
    shuffle<Result,FirstArgs,SecondArgs>(
                Result(*SecondArgs)(*FirstArgs) f)
            given FirstArgs satisfies Anything[]
            given SecondArgs satisfies Anything[]
                => flatten((SecondArgs secondArgs)
                    => flatten((FirstArgs firstArgs)
                        => unflatten(unflatten(f)(firstArgs))(secondArgs)));