input: def reverse_string(string: str) -> str:
      """
      Optimize the given function to reverse a string. The original function iterates 
      through each character of the string and builds the reversed string. The optimized
      function should use a more efficient method to reverse the string.
  
      >>> reverse_string("hello")
      'olleh'
      >>> reverse_string("python")
      'nohtyp'
      """
output:     return string[::-1]