I'm going to restate and stand by my guess of the first thread just because, well, why not.
There once was a man called Boswell.
We've been told to call him "Bos" for short, so there must be another way of saying "walked up the post office steps".
If "There one was a woman called Boswell. For short they called her Bos. And she walked up to the library" works too, then the answer must be some common way of describing the action of going up the post office steps or approaching the library. And that then follows the Bos...
Bos approaches? Bos arriving? Bos nearing the building??
BOSNIA something??
Bos near and he's a go in-ah.
...Bosnia and Herzegovina.
Not funny, not clever, don't care. I'm sticking my flag in the ground with this one.