#!/usr/bin/env python
#-*-coding:utf-8-*-
import copy
def func(args):
    args.append("123")
li=["1","2","3"]
def func2(args):
    l=copy.deepcopy(args)
    l.append("123")
    print("l=",l)
func2(li)
print(li)

def func3(arg):
    if len(arg)>2:
        del arg[2:]
li=[11,22,33,44]
func3(li)
print(li)

def func4(arg):
    arg=123
li = [11,22,33,44]
func4(li)
print(li)

结果：

l= ['1', '2', '3', '123']
['1', '2', '3']
[11, 22]
[11, 22, 33, 44]