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

Inizia esaminando la PR collegata gh-138217, quindi confronta le sezioni del tutorial sulle list comprehensions, del riferimento alle espressioni e del glossario indicate nell’issue. Il lavoro è completato quando la documentazione spiega che le comprehensions supportano più clausole if e include un esempio rappresentativo, aggiungendo la motivazione se i riferimenti esistenti la supportano.