Python newbies often have some confusion about how to make one-element tuples. VenkataSubramanian provided a nice summary of Python's tuple syntax [1].

Zero Element Tuples

In Python, zero-element tuples look like:

()

In this form, unlike the other tuple forms, parentheses are the essential elements, not commas.

One Element Tuples

One-element tuples look like:

1,

The essential element here is the trailing comma. As for any expression, parentheses are optional, so you may also write one-element tuples like

(1,)

but it is the comma, not the parentheses, that define the tuple.

Multiple Element Tuples

In Python, multiple-element tuples look like:

1,2,3

The essential elements are the commas between each element of the tuple. Multiple-element tuples may be written with a trailing comma, e.g.

1,2,3,

but the trailing comma is completely optional. Just like all other expressions in Python, multiple-element tuples may be enclosed in parentheses, e.g.

(1,2,3)
or
(1,2,3,)

but again, it is the commas, not the parentheses, that define the tuple.

[1] http://mail.python.org/pipermail/python-list/2005-June/284208.html