I've just had a brainwave that may give an even less invasive implementation of PEP 671. It relies on every function having a dict, as provided by https://www.python.org/dev/peps/pep-0232/.

Consider:

def fn(a, b, c): pass
fn.__wibble__ = 123
fn.__wibble__ # Give 123, of course.

Now consider:

@wibble

def fn(a, b, c=None):
'''Usual docstring goes here.'''
if c is None: c = []

'#wibble'

return c.extend([a, b])

The @wibble decorator sets fn.__wibble__ to point to the end of the line just before '#wibble'.

We can now define Help(fn) to produce something like:

fn(a, b, c=None)

Usual docstring goes here.

if c is None: c = []

There we go. The functionality asked for, in a way that works with existing Python. If nothing else, we can use this for experiments to explore the idea. Often in Python there are functions whose source is self-explanatory.

Example:

@wibble
def fahr_to_cent(fahr):
return (fahr - 32) * 5 /9
'#wibble'

And now for Help(fahr_to_cent) we get:

fahr_to_cent(fahr)

--
return (fahr - 32) * 5 /9

Final word. Does anyone use PEP 232, function attributes? If not, perhaps remove it as a waste of space.

with kind regards

Jonathan