code: def is_named_tuple(cls):
      
      b = cls.__bases__
      if len(b) != 1 or b[0] != tuple:
          return False
      f = getattr(cls, "_fields", None)
      if not isinstance(f, tuple):
          return False
      return all(type(n) == str for n in f)
docs: Return True if cls is a namedtuple and False otherwise.