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

先檢視連結的 PR gh-138217，然後比較 issue 中提到的列表推導式教學、運算式參考和術語表區段。完成條件是文件說明 comprehensions 支援多個 if 子句，並包含一個具代表性的範例；如果現有參考資料能夠支持該理由，則加入相應的理由。