> dic['name']='zhangsan'
> dic

{'name': 'zhangsan'}

> key='age'
> value=30
> dic[key]=value
> dic

{'age': 30, 'name': 'zhangsan'}

> dic.setdefault('sex','male')
'male'
> key='id'
> value='001'
> dic.setdefault(key,value)
'001'
> dic
{'id': '001', 'age': 30, 'name': 'zhangsan', 'sex': 'male'}

> for key in dic:
...   print 'key is %s,value is %s'%(key,dic[key])
...
key is id,value is 001
key is age,value is 30
key is name,value is zhangsan
key is sex,value is male

> for key,value in dic.items():
...   print 'key is %s,value is %s'%(key,value)
...
key is id,value is 001
key is age,value is 30
key is name,value is zhangsan
key is sex,value is male