A simple test of annotations, generating extended docstrings

doc.py

def doc(f):
	newdoc = f.__doc__ and [f.__doc__, ''] or []
	c = f.__code__
	ann = f.__annotations__
	max_i = c.co_argcount + c.co_kwonlyargcount
	for arg_index in range(max_i):
		name = c.co_varnames[arg_index]
		if name in ann:
			newdoc.append(name + ': ' + str(ann[name]))
		else:
			newdoc.append(name)
	if c.co_flags & 4:
		name = c.co_varnames[max_i]
		if name in ann:
			newdoc.append('*' + name + ': ' + str(ann[name]))
		else:
			newdoc.append('*' + name)
		max_i += 1
	if c.co_flags & 8:
		name = c.co_varnames[max_i]
		if name in ann:
			newdoc.append('**' + name + ': ' + str(ann[name]))
		else:
			newdoc.append('**' + name)
	if 'return' in ann:
		if newdoc and newdoc[-1]:
			newdoc.append('')
		newdoc.append('Returns ' + ann['return'])
	f.__doc__ = '\n'.join(newdoc)
	return f

test.py

@doc
def do_something(a: "the first number", b: "the second number", *args: "other arguments") -> "the fudge of a and b":
	"""Number fudger"""
	return a*b - a - b

print(do_something.__doc__)
# prints:
# Number fudger
#
# a: the first number
# b: the second number
# *args: other arguments
#
# Returns the fudge of a and b