How does Python's comma operator works during assignment?

Question

I was reading the assignment statements in the Python docs ( http://docs.python.org/reference/simple_stmts.html#assignment-statements ).

In that it is quoted that:

Answer 1

Python does not have a "comma operator" as in C. Instead, the comma indicates that a tuple should be constructed. The right-hand side of

a, b = a + b, a

is a tuple with th two items a + b and a.

On the left-hand side of an assignment, the comma indicates that sequence unpacking should be performed according to the rules you quoted: a will be assigned the first element of the tuple, b the second.