from functools import reducedef str2float(s):    flag = []    def f(x, y):        if y == '.':            flag.append(1)            return x        elif flag == []:            return x * 10 + y        else:            flag[0] *= 0.1            return x + y * flag[0]    return reduce(f, [v if v == '.' else int(v) for v in s])