some good python page

http://www.python.org/doc/essays/list2str.html

http://www.python.org/dev/peps/pep-3119/
http://www.ibm.com/developerworks/cn/linux/l-python3-1/
http://docs.python.org/library/abc.html

http://www.ibm.com/developerworks/cn/linux/theme/special/index.html#python

  http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html
http://www.python.org/dev/peps/pep-0008/

it is really cool of python3 ABC module.