> P.S. in my recommended API, and despite what I said above about preferring explicit kwarg invocation, a "just the port" use is one spot where I could see users using just-an-arg:

That's correct, but you would have a hard game convincing me that any of these are not clear (assuming the reader understands what a remote tunnel is in the first place):

```
remote_tunnel(8000)
remote_tunnel(8000, 4000)
remote_tunnel(8000, "dbserver:4000")
remote_tunnel(8000, "dbserver")
remote_tunnel("*:8000", 4000)
```