+ def issubset(self, other):
+ return self <= other
+
+ def issuperset(self, other):
+ return self >= other
+
+ def union(self, other):
+ return self | other
+
+ def intersection(self, other):
+ return self & other
+
+ def difference(self, other):
+ return self - other
+
+ def symmetric_difference(self, other):
+ return self ^ other
+
+ def copy(self):
+ return set(self)
+