>>> single = (1)
>>> type(single)
<type 'int'>
>>> single = (1,)
>>> type(single)
<type 'tuple'>
>>> single
(1,)
Immutable, aren't they?
>>> galileo = ([],)
>>> galileo[0].append("And yet it moves!")
>>> galileo
(['And yet it moves!'],)
But this isn't possible:
>>> galileo[0] = [3434,3434]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
It doesn't work with (1), because this is not a tuple instance but
an expression, i.e. a 1 in parenthesis.