定义代码块的环境的名称空间和使用它的函数之间的作用域本质上是一个作用域：该作用域是闭合的。

The scope between the name space of the environment that defines the code block and the function that USES it are essentially one scope: the scope is closed.

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假如变量未在任何块里申明，它的作用域就是从申明它的地方开始，到文件的结尾。

If the variable wasn't declared in any block, its scope is from the place it was declared to the end of the file.

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闭包可被视作一个遵循特别作用域规则且可以用作参数的代码块。

Think of a closure as a code block that you can use as an argument, with special scoping rules.

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