my \A = set <John Serena Bob Mary Serena>;my \B = set <Jim Mary John Jim Bob>;say A ∖ B; # Set subtractionsay B ∖ A; # Set subtractionsay (A ∪ B) ∖ (A ∩ B); # Symmetric difference, via basic set operationssay A ⊖ B; # Symmetric difference, via dedicated operator