python报错TypeError: ‘NoneType‘ object is not subscriptable的解决方法

  for i in range(2000):
    read_lines = random.shuffle(read_lines) # 问题出在这里了
    print(read_lines)

>>TypeError: 'NoneType' object is not subscriptable

  def shuffle(self, x, random=None):
    """
    Shuffle list x in place, and return None.

    Optional argument random is a 0-argument function returning a
    random float in [0.0, 1.0); if it is the default None, the
    standard random.random will be used.

    """

    if random is None:
      randbelow = self._randbelow
      for i in reversed(range(1, len(x))):
        # pick an element in x[:i+1] with which to exchange x[i]
        j = randbelow(i+1)
        x[i], x[j] = x[j], x[i]
    else:
      _int = int
      for i in reversed(range(1, len(x))):
        # pick an element in x[:i+1] with which to exchange x[i]
        j = _int(random() * (i+1))
        x[i], x[j] = x[j], x[i]

  for i in range(2000):
    random.shuffle(read_lines)
    print(read_lines)
    content_list = []