input: 
  def get_stats_for_string(string):
      """ Calculate the maximum, minimum and mean number of elements in a given string.
      >>> get_stats_for_string("abcdef")
      ('f', 'a', 99.5)
      >>> get_stats_for_string("xyz")
      ('z', 'x', 305.0)
      """
      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)
  
output:     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)