from collections import Counter
a = ['apple', 'orange', 'computer', 'orange']
b = ['computer', 'orange']

ca = Counter(a)
cb = Counter(b)
ca + cb  # Counter({'orange': 3, 'computer': 2, 'apple': 1})


# 进一步抽象
def sumc(*c):
    if (len(c) < 1):
        return
    mapc = map(Counter, c)
    s = Counter([])
    for ic in mapc:
        s += ic
    return s


#Counter({'orange': 3, 'computer': 3, 'apple': 1, 'abc': 1, 'face': 1})
sumc(a, b, ['abc'], ['face', 'computer'])