Function Set-Equal

Part of:

package metabang.utilities
( set-equal < list1 > < list2 > &rest < args > &key < test > < key > )

Returns t if list1 and list2 are equal (as sets). If list1 and list2 are not
equal returns (as multiple values) nil and two lists. The first list contains the
elements in list1 and not in list2 and the second list contains elements in list2
and not in list1.