So I'm working on an easy leetcode problem and I've run into this small error. When 2 of the same number are in a list it refuses to add them together. I made it where it would ignore it if it was the same index but that has the effect of ignoring 2 of the same numbers for some reason. Here is the code

```
def twoSum(nums, target):

    for x in nums:
        for z in nums:
            if nums.index(z) == nums.index(x):
                pass
            else:
                res = x + z
                if res == target:
                    result = [nums.index(x), nums.index(z)]
                    return result

newList = twoSum([3,2,3,7], 6)

print(newList)

```

Is there anything I'm doing wrong here that makes it pass over both 3's and return None?