I don't think that a new parameter format is sufficient. For the message in this call the new parameter isn't even needed, you'd "just" have to ensure that enough information is available in convertsimple to create a more useful message.

That said, that is far from a trivial change, more so because the PyArg_Parse family of functions can parse fairly complicated argument structures in one go (such as using ``PyArg_Parse(args, "(si)", &host, port)`` to unpack the tuple in the first (and only) argument).