input: Write a python function to reverse the characters of each word in a given string.
  assert reverseWords("Hello World") == "olleH dlroW"
  assert reverseWords("Python is fun") == "nohtyP si nuf"
  assert reverseWords("Reverse each word") == "esreveR hcae drow"
output: def reverseWords(s: str) -> str:
      return ' '.join(word[::-1] for word in s.split())