How can I make the rgb a rainbow like those fancy chairs?

1
0
240
S
Swagmaster696969Help

I tried using variables but that didnt work, the code is
init = function() r=0 b=0 g=0 end

draw=function() screen.clear() screen.setAlpha(1) r=r+1 g=g+2 b=b+3 screen.fillRect(0,0,200,80, "rgb(r, g, b)") if r == 255 then r=0 end if g == 254 then g=0 end if b==255 then b=0 end end

and the colours of the box don't change, it is very annoying >:(