Is there an meaning of '[[]]' in a list?

[Peter Otten]

fl wrote:

> Hi,
> In the previous exercises, I see list:
> cc=[[],[],[]]
> 
> Then, I can have this:
> 
> ccc=[[[]],[[]],[[]]]
> 
> I can also have
> 
> ccc[0]
> Out[158]: [[]]
> 
> ccc[0]='o'
> 
> ccc
> Out[163]: ['o', [[]], [[]]]
> 
> 
> I have question: Is there any difference between [[]] and []?
> [[]] can have deeper assignment and use than
> 
> ccc[0]='o'

I'm sure with a little effort and a few experiments on the commandline you 
can answer your question yourself. Please limit your posts to c.l.py to 
those questions that are a little harder.

Hint: when you experiment with nested lists use numbers, not strings as list 
entries that are not lists themselves. Strings can confuse you about the 
nesting level:

>>> items = ["foo"]
>>> items[0]
'foo'
>>> items[0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0]
'f'