how to detect the character encoding in a web page ?

[iMath]

在 2012年12月24日星期一UTC+8上午8时34分47秒，iMath写道：
> how to detect the character encoding  in a web page ?
> 
> such as this page 
> 
> 
> 
> http://python.org/

but how to let python do it for you ? 

such as these 2 pages 

http://python.org/ 
http://msdn.microsoft.com/en-us/library/bb802962(v=office.12).aspx

how to  detect the character encoding in these 2 pages  by python ?