[Tutor] python 2D list

[Yuanxin Xi]

I'm a Python newbie and still exploring, just surprised to see this 2D 
list assignment while debugging.

 >>> a = [[0] *3] *4
 >>> a
[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]
 >>> a[1][2] = 1
 >>> a
[[0, 0, 1], [0, 0, 1], [0, 0, 1], [0, 0, 1]]

why is that a[0][2] a[1][2] a[2][2] a[3][2] are all assigned to 1 
instead of only a[1][2] = 1?  This is a little confusing and 
inconsistent with almost all other languages.  Could anyone please help 
explain the assignment mechanism here?  Thanks