input: Write a python function to check whether all characters of a given string are the same.
  assert allCharsSame("aaaa") == True
  assert allCharsSame("abc") == False
  assert allCharsSame("") == True
  assert allCharsSame("zzzzzz") == True
  assert allCharsSame("ababa") == False
output: def allCharsSame(s: str) -> bool:
      return all(c == s[0] for c in s) if s else True