python函数调用后结果疑惑

def addDict(dict1,dict2):
    dict={}
    for k in dict1.keys():
        dict[k]=dict1[k]
    for k in dict2.keys():
        dict[k]=dict2[k]
    return dict

x={1:1}
y={2:2}
为什么调用addDict(x,y)后结果为{0: {1: [1]}, 1: {2: [2]}}
[解决办法]
我运行了没有出现你说的现象，要么你贴错代码了？

[root@RHEL6A scripts]# more py3.py 
#!/usr/bin/env python

def addDict(dict1,dict2):
    dict={}
    for k in dict1.keys():
        dict[k]=dict1[k]
    for k in dict2.keys():
        dict[k]=dict2[k]
    return dict


x={1:1}
y={2:2}
return1=addDict(x,y)
print return1

[root@RHEL6A scripts]# ./py3.py 
{1: 1, 2: 2}