For tokenize.py, 'def' is not a keyword but just a simple identifier.

>>> tokens = tokenize.generate_tokens(io.StringIO('async def foo(): pass').readline)
>>> pprint.pprint(list(tokens))
[TokenInfo(type=55 (ASYNC), string='async', start=(1, 0), end=(1, 5), line='async def foo(): pass'),
 TokenInfo(type=1 (NAME), string='def', start=(1, 6), end=(1, 9), line='async def foo(): pass'),
 TokenInfo(type=1 (NAME), string='foo', start=(1, 10), end=(1, 13), line='async def foo(): pass'),
 TokenInfo(type=53 (OP), string='(', start=(1, 13), end=(1, 14), line='async def foo(): pass'),
 TokenInfo(type=53 (OP), string=')', start=(1, 14), end=(1, 15), line='async def foo(): pass'),
 TokenInfo(type=53 (OP), string=':', start=(1, 15), end=(1, 16), line='async def foo(): pass'),
 TokenInfo(type=1 (NAME), string='pass', start=(1, 17), end=(1, 21), line='async def foo(): pass'),
 TokenInfo(type=0 (ENDMARKER), string='', start=(2, 0), end=(2, 0), line='')]
>>> 'def' in keyword.kwlist
True
>>> tokens = tokenize.generate_tokens(io.StringIO('def foo(): pass').readline)
>>> pprint.pprint(list(tokens))
[TokenInfo(type=1 (NAME), string='def', start=(1, 0), end=(1, 3), line='def foo(): pass'),
 TokenInfo(type=1 (NAME), string='foo', start=(1, 4), end=(1, 7), line='def foo(): pass'),
 TokenInfo(type=53 (OP), string='(', start=(1, 7), end=(1, 8), line='def foo(): pass'),
 TokenInfo(type=53 (OP), string=')', start=(1, 8), end=(1, 9), line='def foo(): pass'),
 TokenInfo(type=53 (OP), string=':', start=(1, 9), end=(1, 10), line='def foo(): pass'),
 TokenInfo(type=1 (NAME), string='pass', start=(1, 11), end=(1, 15), line='def foo(): pass'),
 TokenInfo(type=0 (ENDMARKER), string='', start=(2, 0), end=(2, 0), line='')]
>>>

Is it normal ?

>>> keyword.iskeyword('pass')
True

There doesn't seem anything particular about def, none of the keywords have "keyword" type, because there doesn't seem to be one: https://docs.python.org/3.6/library/token.html

why do you close it ?

def is not a keyword and it's a problem, how do you define a function is def is not a keyword.

async is not a keyword but if you used it before 'def', async will become a keyword.


have you checked the output from the tokenizer ? in the output, def is a NAME and not DEF.

Perhaps, my example wasn't as self-explanatory as I hoped. def is not DEF in the token list, because there isn't such a token DEF, as there isn't a token PASS or a token for any other keyword. The fact that there is an ASYNC and AWAIT tokens is something completely different and is not related to keywords as such. The link I provided lists all the tokens in the token module.

I think the error here is that tokenize returns type=ASYNC for 'async', instead of type=NAME.

how to know if it's an issue or not? we can ask to Yury

It does not currently work, because the docstring logic looks for a string, not an expression. And an f-string is an expression.

It would require changing the compiler to evaluate the f-string expression.

??

He probably mistook this for #25179

Oops, wrong issue. Ignore my last comment. I shouldn't do two things at once.

Stéphane, sorry for not replying earlier, emails from bugs.python.org sometimes go to spam.

[TokenInfo(type=55 (ASYNC), string='async', start=(1, 0), end=(1, 5), line='async def foo(): pass'),
 TokenInfo(type=1 (NAME), string='def', start=(1, 6), end=(1, 9), line='async def foo(): pass'),

^-- this is indeed correct.  Right now async/await are treated specially in tokenizer.c & parser, and tokenize.py simply mimics their behaviour.