code: def is_date(thing):
      
      # known date types
      date_types = (datetime.datetime,
                    datetime.date,
                    DateTime)
      return isinstance(thing, date_types)
docs: Checks if the given thing represents a date
  
      :param thing: The object to check if it is a date
      :type thing: arbitrary object
      :returns: True if we have a date object
      :rtype: bool