We want you to make a function which checks if the given word has major vowel harmony. According to TDK, in a word, hard vowels (a, ı, o, u) must be followed by hard vowels and soft vowels (e, i, ö, ü) must be followed by soft vowels.
You can check your code with yarn test command. When all tests pass, you probably made a correct implementation. You don't need to cover special cases, uppercase letters. Given word must be a Turkish word already. So, please don't try to understand whether the word is Turkish or not, just treat as like it's Turkish.
You can find more information about Major Vowel Harmony in TDK website.