```
func reverseVowels(s string) string {
r := []byte(s)
var index []int
for i, v := range s {
if v == 'a' || v == 'e' || v == 'i' || v == 'o' || v== 'u' ||
v == 'A' || v == 'E' || v == 'I' || v == 'O' || v == 'U' {
index = append(index, i)
}
}
if len(index) >= 2 {
i := 0
j := len(index) - 1
for i < j {
r[index[i]], r[index[j]] = r[index[j]], r[index[i]]
i++
j--
}
}
return string(r)
}
```