eople = {

'alice' : {
    'phone': '2341',
    'addr' : 'foo drive 23'
},

'beth' : {
    'phone' : '9102',
    'addr'     : 'bar street 42'
},

'cecil' : {
    'phone' : '3158',
    'addr'  : 'baz avenue 90'
}
    }

labels = {
    'phone' : 'phone number',
    'addr'  : 'address'
}

name = raw_input('name: ')
request = raw_input('phone number (p) or address(a)?')

key = request

if request == 'p' : key = 'phone'
if request == 'a' : key = 'addr'

person = people.get(name,{}) 
label = labels.get(key,key)    
result = person.get(key, 'not available')

print "%s's %s is %s." % (name,label,result)

#if name in people : print "%s's %s is %s." % (name,labels[key], people[name][key])

最近开始学python基础教程这本书，今天看到get（）的用法有点懵，想问一下倒数第5行代码，为什么people字典中没有name键的时候要返回一个空字典，作用是什么？