python中值传递和引用传递的区别

def param_test(obj):

    obj += obj

    print('形参值为:', obj)

print('*******值传递*****')

a = '码农飞哥'

print('a的值为：', a)

param_test(a)

print('实参的值为:', a)

print("*******引用传递*****")

b = [1, 2, 3]

print('b的值为：', b)

param_test(b)

print('实参的值为：', b)