I like the idea behind this, and I appreciate that it makes a complicated concept dirt-simple to use, but I think it's a little too simple. You can't diagram an

I like the idea behind this, and I appreciate that it makes a complicated concept dirt-simple to use, but I think it's a little too simple. You can't diagram anything but a closed system, and most things are better modeled as open ones; the one addition of constant-up or constant-down nodes would make this much more useful.