Giving variables a data type, even with something as generic as xs: string, traps the unexpected absence of the attribute-something that has saved my day more often than I would like to admit.

为变量提供一个数据类型，可以是xs： string这样的一般类型，捕捉预计之外的属性缺失—这帮助我节约了大量时间。

youdao

Nil is the type of the special value nil and is used to represent the absence of a value.

nil是值为nil的一种特殊类型，用来表示没有值。

youdao

All of the above can be conditional upon the operating system type and revision, time of day, arbitrary user-defined classes, presence or absence of files, directories, or data in files, and so on.

上述所有这些根据操作系统类型和修订版本、一天中的时间、任意用户定义的类、文件中文件、目录或数据的有无等等可以是有条件的。

youdao

So in the absence of this type of evidence, we have to rely on what we know about bipolar disorder in general.

CNN: Can a person 'discourage' bipolar disorder?

Last year's fight over the arcane concept of network neutrality--the absence of restrictions on the type of content that can move over the privately owned networks that comprise the Internet--was just a preview.

FORBES: Spectrum Warriors

Community and governance: vast swathes of the literature are about how institutions, the presence or absence of corruption (even the type of it) influence growth.

FORBES: World Happiness Report: Even Jeff Sachs and Richard Layard Don't Really Believe It