A.union(B) or AlB .union) The .union0 operator returns the union of a set and the set of elements in an iterable Sometimes, the operator is used in place of .union0 operator, but it operates only on the set of elements in set. Set is immutable to the union0 operation (or operation). Example >sset("Hacker") >>print s.union("Rank") set(['a', 'R', c', 'r', 'e', 'H','k', 'n']) >>> print s.union (set(L'R', 'a', 'n', 'k'])) set(['a', 'R', 'c','r', 'e', 'H', 'k', 'n']) >>> print s.union(['R', 'a', 'n', 'k']) set(['a', 'R', 'c', 'r', 'e', 'H', 'k', 'n')) >>> print s.union (enumerate(['R', 'a', 'n', 'k'])) set(['a', 'c', 'r', 'e', (1, 'a, (2, 'n'), 'H', 'k', (3, "k'), (0, 'R')]) >>print s.union (["Rank": 1) set (['a', 'c', 'r', 'e', 'H', 'k' 'Rank']) >>> set("Rank") set(['a', 'R', c', 'r', 'e', 'H','k', 'n'])