
  [;1m-spec is_set(AnySet) -> Bool when AnySet :: anyset(), Bool :: boolean().[0m

  Returns [;;4mtrue[0m if [;;4mAnySet[0m appears to be an unordered set, and [;;4m[0m
  [;;4mfalse[0m if [;;4mAnySet[0m is an ordered set or an atomic set or any other
  term.

  Note that the test is shallow and this function will return [;;4mtrue[0m
  for any term that coincides with the representation of an
  unordered set. See also note on data types.
