Multiple variable affectations.
Input value to affect.
Affected value (to in1, in2, in3 according to the pressed affect button).
Button to affect the output value to the in1, 2 and 3 value.
The affectation is processed in the order 1,2 and 3. So, for example, if you press the affect1, affect2 and affect3 buttons at the same time,
the output value is set to in3.