在这个示例中，末尾的空列表意味着您构造了一个结构良好(合适)的列表。

In this example, the empty list at the end means that you have constructed a well-formed (proper) list.

youdao

这种枚举类型是诸如下拉列表等可视表单构造的良好选择，它允许在一个有限的可能选项列表中选择一个选项。

Enumerated types such as this are good candidates for visual form constructs such as a drop-down list, which permits the selection of one option among a finite list of possibilities.

youdao

因此，良好的实践是在添加和删除新的表达式之前，将返回列表复制到一个新的列表中。

So a good practice is to copy the returned list into a new list before adding or removing new expressions.

youdao