I just remembered a programming technique from the days when I had access to a Commodore Pet.

I wanted a graph plotting program to allow users to type in a function and plot it. I could have written an expression parser. But far easier was to print out a line of code for the function and a RUN command (or similar), place the cursor in the right place, put a carriage return or two into the keyboard buffer, and stop the program. IIRC the Pet literally read input from the frame buffer (which allowed you to edit code by cursoring into the output of LIST) so this would update your program and continue.