input: Write a function to calculate the maximum, minimum, and mean number of elements in a given string. The function should return a tuple containing the maximum, minimum, and mean elements. The mean should be calculated by summing all the elements (characters) in the string and dividing by the total number of elements.
  
  def get_stats_for_string(string):
      num_elements = len(string)
      max_element = max(string)
      min_element = min(string)
      mean_element = sum(string) / num_elements
      return (max_element, min_element, mean_element)
  
  assert get_stats_for_string("abcd") == ('d', 'a', 99.0)
  assert get_stats_for_string("12345") == ('5', '1', 52.0)
  assert get_stats_for_string("") == (None, None, None)
  assert get_stats_for_string("A") == ('A', 'A', 65.0)
  assert get_stats_for_string("!@#") == ('#', '!', 35.0)
output: def get_stats_for_string(string):
      if not string:
          return (None, None, None)
      num_elements = len(string)
      max_element = max(string)
      min_element = min(string)
      mean_element = sum(ord(char) for char in string) / num_elements
      return (max_element, min_element, mean_element)