I'm trying to make a large document which has many index pages. Because the document is supposed to be rather sprawling, many mentions of certain topics will then link to those topics so that you don't have to go hunting for them elsewhere if you want clarification.
Normally, you could simply make a 'back' button by making a link which goes to the last passage, but that becomes more complex when there can be more than one possible passage that you came from. I've looked around, and previous() came up, but that's obviously for Sugarcube, and I'm using Harlowe.
So; how would I make a button which goes to the last passage the user was on?