I knew white space means a lot in Python (Disc: newbee and learning Python still!). Just found this, and thought someone out there might be able to throw some more light.
Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win32
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>>> a=[1,2,3]
>>> b=a
>>> b
[1, 2, 3]
>>> a=[1]
>>> b
[1, 2, 3]
>>> id(a)
18704984
>>> id(b)
18721728
>>> c = [4, 5, 6]
>>> d = c
>>> id(c)
10755928
>>> id(d)
10755928
>>> print c, d
[4, 5, 6] [4, 5, 6]
>>> c = [7]
>>> print c, d
[7] [4, 5, 6]
>>> e = c
>>> c.append(8)
>>> print c, d, e
[7, 8] [4, 5, 6] [7, 8]
>>>
c = [4,5,6] is creating a new list, and assigning it to c; not modifying the list that c pointed to. The '=' operator simply associates an object reference to a variable. Going d=c is copying the reference to an object from one variable to another.
