python怎么传参数

from ctypes import *

import os.path 

import sys

def test(c):

    print "test before "

    print id(c)

    c+=2

    print "test after +"

    print id(c)

    return c

def printIt(t):

    for i in range(len(t)):

        print t[i]

if __name__=="__main__":

    a=2

    print "main before invoke test"

    print id(a)

    n=test(a)

    print "main afterf invoke test"

    print a

    print id(a)

>>>

main before invoke test

39601564

test before

39601564

test after +

39601540

main afterf invoke test

2

39601564