[Python-Dev] How to document functions with optional positional parameters?

[Serhiy Storchaka]

How to document functions with optional positional parameters?

For example binascii.crc32(). It has two positional parameters, one is 
mandatory, and one is optional with default value 0. With Argument 
Clinic its signature is crc32(data, crc=0, /). In the documentation it 
is written as crc32(data[, crc]) (and noted that the default value of 
the second parameter is 0). Both are not valid Python syntax. Can the 
documentation be change to crc32(data, crc=0)?

Related issues:

https://bugs.python.org/issue21488 (changed encode(obj, 
encoding='ascii', errors='strict') to encode(obj, [encoding[, errors]]))

https://bugs.python.org/issue22832 (changed ioctl(fd, op[, arg[, 
mutate_flag]]) to ioctl(fd, request, arg=0, mutate_flag=True))

https://bugs.python.org/issue22341 (discussed changing crc32(data[, 
crc]) to crc32(data, crc=0))