CheckIn is a way to let other people know what the heck you're up to.
It's essentially a status. But like. For your terminal. Has that been done already? Has to have been, right?
checkin set [--include-wd]
--include-wd will include your current working directory in your message.
checkin get [--freshness=14]
--freshness controls how new (in days) messages must be in order to be printed.