I stumbled across the problem reported in https://bugs.python.org/issue25030 on Python 3.8:

>>> with open('x.txt', 'a') as fp:
...   fp.seek(0, whence=os.SEEK_END)
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
TypeError: seek() takes no keyword arguments

Which I coded with a keyword argument because the documentation says so:

   seek(offset, whence=SEEK_SET)

See https://docs.python.org/3.8/library/io.html#io.IOBase.seek

The fix for issue issue25030 changed the documentation to:

   seek(offset[, whence])

and supposedly was integrated into 2.7, 3.4, and the default branch back then.

It seems the fix got lost?

For the record, https://github.com/python/cpython/pull/14691/files reintroduced `whence=SEEK_SET`.

Since we have positional-only argument, can we document it as `seek(offset, whence=SEEK_SET, /)`?

Thanks for referencing the PR that reintroduced the old way of documenting it.

From my perspective, the proposal is fine. There are already some cases where it is documented like that, e.g. str.removeprefix(prefix, /).

Just wanted to add that I encountered this today, went to file a ticket, and found this one. I'm fine with either style of documentation.