How to get ZSH previous command's history number in prompt?

Question

I'm wanting to add the previous command's history number to my prompt, as well as the exit code.

At present,

%h[%?]

Gives me the current history number, as well as the last exit code. What I'd really like is an expansion for %h-1, but I'm not sure if that is possible?

Answer 1

The answer, courtesy of /r/commandline on Reddit is:

 PS1='$[HISTCMD-1][%?] %#'