
  [;1m-spec intersection(SetOfSets) -> Set[0m
  [;1m                      when Set :: a_set(), SetOfSets :: set_of_sets().[0m

  Returns the intersection of the set of sets [;;4mSetOfSets[0m.

  Intersecting an empty set of sets exits the process with a [;;4mbadarg[0m
  message.
