A function inputs a single number and outputs a single number. (e.g. $y = f(x)$)
What mathematical object inputs a sequence, or even just a vector or tuple?
I understand that a function doesn't have to take a single number and output a single number. But what do you call the functions that don't? Can you give me some Google-able terms, please?
Example #1: the "derivative" (calculus) operation inputs a function and outputs a function. So it is clearly different than the basic/classic/algebraic "function" $y = f(x)$.
Example #2: the "union" (set-theory) operation inputs two sets and outputs a set.
Can you provide an example of any operation that inputs a sequence?