Press A to Increment up to 1
Press B to Increment down to 0
Press reset to set output to zero. This is clamped at 0 and 1, I'll list the unclamped codes below

 var: output = Y+(B+X)
 var: output = Y+(B-X) 

These Increment Y by 1+X, set X to be the number to increment by minus 1, make sure to set the switch input to 0 after the function runs, as the number will keep moving up or down.

How to use buttons with FT:

Set the inputid XML attribute to any name that is reasonable for repeated use, I used ButtonA and ButtonB.

In the variable menu, declare two variables

 var buttoninputA = ButtonA
 And
 var buttoninputB = ButtonB

You now have two variables controlled by buttons or switches. You now must choose how you want these input devices to behave, there are three options, I'll list them below. In order to change the behavior, you must change interactionType to one of these.

Option 1: Once
Pressing a button or flipping a switch with this option will forcefully set it's output to 1 for a single frame, then will not alter the value further. The value will not return to zero until another operation sets it to zero.

Option 2: Continuous
As long as a button or switch is held, it will set the output to 1, when you let go, it will stay 1 until changed by another operation.

Option 3 Toggle
A button or switch will output a 1 until turned off, then the value can be changed by another operation.

After you pick your option, you can do what you need with the switches.