python 两个或多个字典合并相加

多个字典合并，相同的key合并相加。

def sum_dict(a,b):
    temp = dict()
    for key in a.keys()| b.keys():　
        temp[key] = sum([d.get(key, 0) for d in (a, b)])
    return temp

def test():
    from functools import reduce
    return print(reduce(sum_dict,[a,b,c]))

a = {'a': 1, 'b': 2, 'c': 3} 
b = {'a':1,'b':3,'d':4}
c = {'g':3,'f':5,'a':10}
test()