Python 今天发布了Python 2.7.4，该版本修正了上百个bugs。
python2.7.x是python2.x系列的最后一个重要版本，它包含了python3.1中的很多重要特性
本次更新的重要特性：
An ordered dictionary type
New unittest features including test skipping, new assert methods, and test discovery
A much faster io module
Automatic numbering of fields in the str.format() method
Float repr improvements backported from 3.x
Tile support for Tkinter
A backport of the memoryview object from 3.x
Set literals
Set and dictionary comprehensions
Dictionary views
New syntax for nested with statements
The sysconfig module
