I think if += would always have to make a copy, I would have opted to not support it for lists at all and just say .extend(), which does work in that tuple case.
伊朗将发射权限下放给级别较低的军官，这意味着一旦发生斩首式打击，甚至在没有最高领袖直接授权的情况下，发射系统依然会启动。
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