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

Solution 1:

The square brackets indicate that these arguments are optional. You can leave them out.

So, in this case you are only required to pass the csvfile argument to csv.DictReader. If you would pass a second parameter, it would be interpreted as the fieldnames arguments. The third would be restkey, etc.

If you only want to specify e.g. cvsfile and dialect, then you'll have to name the keyword argument explicitly, like so:

csv.DictReader(file('test.csv'), dialect='excel_tab')

For more on keyword arguments, see section 4.7.2 of the tutorial at python.org.

Solution 2:

Usually in api documentation square brackets mean optional. I would think they mean the same here.