What do square brackets, "[]", mean in function/class documentation?

user_173288 0
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I am having trouble figuring out the arguments to csv.dictreader and realized I have no clue what the square brackets signify.

From the docmentation:

class csv.DictReader(csvfile[, fieldnames=None[, restkey=None[, restval=None[, dialect='excel'[, *args, **kwds]]]]])

I'd appreciate a summary of the arguments to the class instantiation.

Thanks

python
4 Answers

This is actually a subset of the widely used notation to unambiguously describe language syntax called Backus-Naur Form (see Wikipedia article for details).

user_2535030
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