person = {'name': '王大锤', 'age': 25, 'height': 178, 'addr': '成都市武侯区科华北路62号1栋101'}
print(person.get('name'))       # 王大锤
print(person.get('sex'))        # None
print(person.get('sex', True))  # True
 

stocks = {
    'AAPL': 191.88,
    'GOOG': 1186.96,
    'IBM': 149.24,
    'ORCL': 48.44,
    'ACN': 166.89,
    'FB': 208.09,
    'SYMC': 21.29
}
stocks2 = {key: value for key, value in stocks.items() if value > 100} //value 大于 100 才会被放到 stocks2 字典中，if value > 100可有可无
print(stocks2)