Ask HN: Terminal Demonstration

Within the last year there was a post about a terminal demonstration program which allowed you to create a file with comments in of the code/commands to type and would then open a new window and type the commands on another screen, in type with your button presses, to make it look like you are typing without making a mistake. My Googlefu is weak and I can't find any trace of it. Does anybody know what I am thinking of any where I can find it?