```
def negated(a):
    a = set(a)
    for i in a:
        a.add(-i)

    return list(a)

```

if `a = [ 3, 4, 5, 6, 7, 8, -3, -4]`. I only want to print the values that have a negated counterpart ex: `3, -3, 4, -4` 

I don't know what's wrong with my code.