class XxxError(Exception):

    def __init__(self , message):

        self = Exception("xxxxx")

        // Exception.__init__(self)

        self.message = message 

def power(x, n=2) :

    if x== 0 and n ==0:

        raise ValueError ("....")

    print ( x ** n)

power(0,0)

def add_list(*elements , l1=[]):

　　length = len(elements)

　　n = 0

　　while n < length :

　　　　l1 = l1 + elements[n]

　　　　n += 1

　　return l1 //默认参数应该指向不变对象

def add(a, b, *numbers ,exten=0):

    length = len(numbers)

    n = 0

    sum_ = 0

    while n < length:

        sum_ += numbers[n]

        n += 1

    return a+b+sum_ + exten

r = add(5,6,6,6,6,6,6,7,8,9)

def print_information ( name , ** values):

    print("name:" , name)

    for key , value in values.item():

        print(key , ":" , value)

print_information("xxx" , age="" , city="guangzhou")

def xxx(name , age , ...):

    if age > 40:

        raise xxxError()

    return "xxxx"

try :

    result = xxx("xxx" , 50 , ...)

except xxxError as ex1:

    print ("xxx..." , ex1)

except xxxError as ex2:

    ...

finally:

    ...