What does [, element] mean?

Question

I was reading the python documentation where I came across elem [,n] this notation for arguments. I have seen such notations in past. Don't just know what they mean. Also, google doesn't support searching brackets.

http://docs.python.org/3.4/library/itertools.html Same use of brackets here. — Jeremy Cochoy, Jul 19 '13 at 17:49
related: [How to read API documentation](http://stackoverflow.com/q/10925478/1048572) — Bergi, Mar 07 '15 at 18:16

score 15 · Accepted Answer · answered Jul 19 '13 at 17:51

The Python documentation has a section about the used notation, which says:

[…] a phrase enclosed in square brackets ([ ]) means zero or one occurrences (in other words, the enclosed phrase is optional).

This notation originates from the Backus–Naur Form (BNF).

score 5 · Answer 2 · answered Jul 19 '13 at 17:49

5

It means that the argument so bracketed is optional.

answered Jul 19 '13 at 17:49

Marcin

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score 0 · Answer 3 · answered Jul 19 '13 at 17:51

0

Generally this means that the parameter within the square brackets is optional; however, without a link to the specific documentation it's hard to say.

answered Jul 19 '13 at 17:51

Joel

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What does [, element] mean?

3 Answers3

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