code: def extend_is_dir(value, minimum=None, maximum=None):
      u
  
      if isinstance(value, list):
          return [is_dir(member)
                  for member in validate.is_list(value, minimum, maximum)]
  
      else:
          return is_dir(value)
docs: u"""
      This function is extended is_dir().
      This function was able to take ListType or StringType as argument.