写python的时候出现了这个错，然后网上的教程的解决方案几乎都是——“重新定义下这个变量”，看的我一脸懵逼后来发现原来是我把return None的方法赋给了变量，之后操作变量导致的，直接上代码
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for i in range(2000):
read_lines = random.shuffle(read_lines) # 问题出在这里了
print(read_lines)
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咋一看是没啥问题，但是一运行就报错
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>>TypeError: 'NoneType' object is not subscriptable
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后来发现原来 random.shuffle这个函数他是return None的，但是我把他赋值给了read_lines，导致后续在操作read_lines的时候一直都是这个报错，包括打印read_lines也报错
这个是random库里面的代码（看他的注释里面说的是return None）
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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]
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解决方案
把上面一行赋值语句改掉就好了
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for i in range(2000):
random.shuffle(read_lines)
print(read_lines)
content_list = []
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