What exactly the third argument of decorated function with api.route does?

[tomoyks]

Here is an example code of responder.

import responder
api = responder.API()

@api.route("/{greeting}")
async def greet_world(req, resp, *, greeting):
    resp.text = f"{greeting}, world!"

if __name__ == '__main__':
    api.run()

I wonder what is the role of third argument asterisk.

I think here is the line which call route function but I couldn't find any part which give value corresponds third augment asterisk.

Please tell me the role of third argument of decorated function with api.route does.
Thank you.

[taoufik07]

Docs: https://www.python.org/dev/peps/pep-3102/

Using * tells python to only accept keyword-only arguments after it (*)

>>> def func(a, b, *, c):
        print(a, b, c)
>>> func(1, 2, 3) # Will raise an error
>>> func(1, 2, c=3) # 1, 2, 3

[tomoyks]

Now it becomes clear, thank you for answering!