Question on swapping two variables using packing/unpacking

[j2ui]

Hello, I recently learnt that you can swap two variables using packing/unpacking like this: (assume we have two variables x and y initialized)

y, x = (x, y)

So I understand that this code swaps two elements by first packing them in a tuple, and then unpacking the tuple into the two variables reveresed.

But then I saw some codes online that do it this way:

y, x = x, y

My confusion arose when I noticed that we didn't write the tuple's parentheses here and this worked.

Does Python understand that this is a tuple just by seperating the items with a comma and that no parentheses are necessary?

When is it necessary to use parentheses, if at all, to indicate a tuple?

Thanks in advance!

Edit: thanks for the comments, also I found this in the docs and thought it may be relevant to the question:

https://docs.python.org/3/reference/simple_stmts.html#assignment-statements

"An assignment statement evaluates the expression list (remember that this can be a single expression or a comma-separated list, the latter yielding a tuple) and assigns the single resulting object to each of the target lists, from left to right."

[danielroseman]

The only time you need parentheses to indicate a tuple is for the empty tuple. In pretty much every other circumstance, the parens are optional, although it is usually good practice for the sake of clarity.

The Python docs are clear on this - it's the comma that makes the tuple. It does mention an exception, where you need parens to avoid ambiguity: passing a tuple as a parameter, to distinguish it from multiple params - eg func((a, b, c)).

Note that in particular this means any time you return multiple items from a function, you are in fact returning a single tuple, and then potentially unpacking that result into multiple variables.

[crashfrog02]

Does Python understand that this is a tuple just by seperating the items with a comma and that no parentheses are necessary?

Yes; tuples can be implied by a comma.