Python - Why these parentheses in if-statement alters the real condition? [duplicate]

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• How to check if one of the following items is in a list? 14 answers

I was doing a leetcode question while I had the following python code:

pairs = [(1,3)]
addend = 3
sum = 4
if ((addend, sum-addend) or (sum-addend,addend)) in pairs:
    print("Pair exists")

The expected output when I ran this code should be

Pair exists

But instead this prints nothing, which I assumed ((addend, sum-addend) or (sum-addend,addend)) evaluates to False.

Then I removed the outer parentheses and made it

if (addend, sum-addend) or (sum-addend,addend) in pairs:
        print("Pair exists") 

This gave me the right output.

My second guess was this pair of redundant parentheses actually calculates ((addend, sum-addend) or (sum-addend,addend)), so I put ((1,3) or (3,1)) in the Python3.7 console directly and that's the output

>>> ((1,3) or (3,1))
(1, 3)

But still this won't make sense since (1,3) is indeed in pairs.

Could anybody explain why putting these parentheses invalidates the statement? Thanks!