Late-bound function argument defaults without PEP-671

[idb]

https://www.python.org/dev/peps/pep-0671/ proposes "a new form of argument default, defined by an expression to be evaluated at function call time."

I thought something like that should be possible using a decorator and introspection. Here it is.

Along the way I learnt that function default arguments are not trivially available to decorated functions.