Five coding challenges

Complete all five in Python. Use functions where helpful. Test edge cases.

1. Reverse a string without using [::-1] (loop only)
2. FizzBuzz for 1–100 (divisible by 3 → Fizz, by 5 → Buzz, both → FizzBuzz)
3. Count vowels in a sentence
4. Find duplicate values in a list
5. Palindrome check — ignore spaces and case