To understand a program, you must become both the machine and the program.
There is no such thing as a free variable.
One can only display complex information in the mind. Like seeing, movement or flow or alteration of view is more important than the static picture, no matter how lovely.
It is easier to change the specification to fit the program than vice versa.
In man-machine symbiosis, it is man who must adjust: The machines can't.
If you have a procedure with 10 parameters, you probably missed some.