Explanation for trailing comma in example from Learning Python?

[Christian Heimes]

Carl Schumann wrote:
> I could see the logic in always or never having a trailing comma.   What
> I don't understand here is why only the single element case has a
> trailing comma.   Any explanations please?

Does this code shad some light on the trailing comma? :)

>>> (1) == 1
True
>>> (1,) == 1
False
>>> type((1))
<type 'int'>
>>> type((1,))
<type 'tuple'>

>>> a = 1
>>> a
1
>>> a = (1)
>>> a
1
>>> a = (1,)
>>> a
(1,)
>>> a = 1,
>>> a
(1,)