<<Yesterday*, while going up the stair.>>

See, -now that's really the only really clever one so far. As to scan, how about "Once, while going..."

But, as long as we're on not-so-very clever ones, I can throw in another (surprise!)

Mary loves to skate
When the wind is cold and brisk
Mary is a little fool
her little asterisk

This is Binky, wishing you a pleasant from the rings of Saturn, signing off.