function main() returns nothing

    number i

    for i = 0 to 15
        setPenColor(i)
        fillBlock(i * 20, (i + 1) * 20)
    endfor

endfunction


function fillBlock(number start, number stop) returns nothing

    number i

    setPenDown()

    for i = start to stop
        setTurtleXY(0, i)
        setAngle(0)
        goForward(30)
    endfor

endfunction