input: Write a python function to reverse a given string using a class method.
  assert reverse_string('hello') == 'olleh'
  assert reverse_string('world') == 'dlrow'
  assert reverse_string('python') == 'nohtyp'
output: class StringManipulator:
      @staticmethod
      def reverse_string(s: str) -> str:
          return s[::-1]
  
  def reverse_string(s: str) -> str:
      return StringManipulator.reverse_string(s)