Document usage of comprehensions with multiple if clauses

Documentation

As noted in the documentation for list comprehensions (and also in the reference docs on expressions, but not in the glossary which refers to an "if clause" in the singular), list/set/dict comprehensions can accept zero or more if clauses like so:

[i for i in range(10) if i % 2 if i % 3]

Looking at the bytecode generated with python -m dis, this appears to be strictly equivalent to:

[i for i in range(10) if i % 2 and i % 3]

(The last if was replaced by and)

It would be nice if this was documented, and ideally with examples.

I'm also personally curious why that feature exists so if someone could point me to an explanation I'd appreciate it. I didn't find anything in what I believe is the original PEP for list comprehensions (PEP 202).

Linked PRs

• gh-138217

首先查看链接的 PR gh-138217，然后比较 issue 中提到的列表推导式教程、表达式参考和术语表部分。完成标准是文档说明 comprehensions 支持多个 if 子句，并包含一个具有代表性的示例；如果现有参考资料能够支持该理由，则添加相应的理由。