python - 两个列表取差集

Question

list1 = ['1', '2', '3', '4']
list2 = ['1', '2', '5', '6']

求取差集：

['3', '4', '5', '6']

Answer 1

雷雷

Answer 2

雷雷

Answer 3

list1 = ['1', '2','3','4']
list2 = ['1', '2', '5', '6']
set1 = set(list2) - set(list1)
set2 = set(list1) - set(list2)
newlist =  list(set1)+list(set2)
print sorted(newlist)

應該還有更簡潔的方法.