brain stuck. whats occurring here?

[Matthew_WARREN at bnpparibas.com]

Hallo,

I'm after

[[[],[],[],[],[]],[[],[],[],[],[]],[[],[],[],[],[]],[[],[],[],[],[]],[[],[],[],[],[]]]

(NxN 'grid', 5x5 in that example, and while typing this up i figured out
how to get it, but I'm still not sure what _was_ happening)


I'm trying

>>>> a=[]
>>> row=[ [] for n in range(0,10) ]
>>> a.extend(row[:])
>>> a
[[], [], [], [], [], [], [], [], [], []]
>>> a[0].extend(row[:])
>>> a
[[[...], [], [], [], [], [], [], [], [], []], [], [], [], [], [], [], [],
[], []]


why isnt that last a

[[[...]],[],[],[],[],[],[],[],[],[]]


Puzzled :)

Matt.
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