OK, then I hope Aaron will come around to the idea that an unapplied
function (sin, f, Lambda) all have nargs which is a *tuple* so you always
know what you are dealing with in code that tests for functions. And then
we just live with the fact that through inheritance foo(*args) will have
the same attribute passed down but that you should use len(foo().args) if
you want the actual number of args.  OR...make the tuple nargs named
`_nargs` and the actual number of args named `nargs`?