Mutable objects inside tuples - good or bad?

[John Ladasky]

I find this programming pattern to be useful... but can it cause problems?

Python 3.3.2+ (default, Feb 28 2014, 00:52:16) 
[GCC 4.8.1] on linux
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>>> a = [1,2,3]
>>> b = [4,5,6]
>>> c = (a,b)
>>> c
([1, 2, 3], [4, 5, 6])
>>> c[0][0] = 0
>>> c
([0, 2, 3], [4, 5, 6])

Comments appreciated.