Using Logisim evolution: In this picture, you can see the keyboard and two TTY$.$ In the first TTY$,$ you will see the normal text, but in the second TTY$,$ you will see an encrypted text. I insert an adder to modify the text, but I need something to not modify when I insert in the keyboard a space bar. What do I need in the circuit to not encrypt the space? Please a step by step guide.