实际上可以使用闭包代替该方法来建立和清除资源。
You could actually use a closure to do the resource setup and cleanup instead.
注意，稍后您也可以使用闭包和引用变量。
Note that you can use closures and reference variables later too.
通常分为常开型，常闭型和自保持式三种。
Usually divided into normally open, normally closed and self-holding three.
汽车有动力转向和中枢锁闭系统。
汽车有动力转向和中枢锁闭系统。
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