练习题

from functools import reducedef str2num(s):    # return int(s)    return float(s)def calc(exp):    ss = exp.split('+')    ns = map(str2num, ss)    return reduce(lambda acc, x: acc + x, ns)def main():    r = calc('100 + 200 + 345')    print('100 + 200 + 345 =', r)    r = calc('99 + 88 + 7.6')    print('99 + 88 + 7.6 =', r)main()