The function swaps the vowels in the input string. It starts with the first and last vowels and continues until it reaches the middle of the string. If there's an odd number of vowels, the middle one stays unchanged. The function appears to be case-insensitive.

[CODE]: 

```python
def swap_vowels(s):
    vowels = "aeiouAEIOU"
    s_list = list(s)
    i, j = 0, len(s) - 1

    while i < j:
        if s_list[i] not in vowels:
            i += 1
            continue
        if s_list[j] not in vowels:
            j -= 1
            continue
        s_list[i], s_list[j] = s_list[j], s_list[i]
        i += 1
        j -= 1

    return ''.join(s_list)
```

This code should approximate the behavior of the function.