setintersection function takes multiple sets and produces a single set
containing only the elements that all of the given sets have in common.
In other words, it computes the
intersection of the sets.
> setintersection(["a", "b"], ["b", "c"], ["b", "d"])[ "b",]
The given arguments are converted to sets, so the result is also a set and the ordering of the given elements is not preserved.