案例：找到多个dict的的公共key
如 {'a':1,'b':2,'c':3}, {'x':1,'b':33,'z':100} 则查找出b
from random import randint, sample
# 生成随机的字典
c1 = {key: randint(1,3) for key in sample('abcdefg',ranint(3,6))}
c2 = {key: randint(1,3) for key in sample('abcdefg',ranint(3,6))}
c3 = {key: randint(1,3) for key in sample('abcdefg',ranint(3,6))}
# 对于固定数量可以使用集合的并集操作
c1.viewkeys() & c2.viewkeys() & c3.viewkeys()
# 对于n个 使用map reduce操作
reduce(lambda old, new: old & new, map(dict.viewkeys, [c1,c2,c3]))
