Correct.way

function up()
uu = req - cur
u = uu * 9
for i=1,u do
rs.setBundledOutput("left", colors.white)
sleep(0.75)
rs.setBundledOutput("left", 0)
sleep(0.06)
end
main()
end

function down()
dd = cur - req
d = dd * 9
for i=1,d do
rs.setBundledOutput("left", colors.black)
sleep(0.75)
rs.setBundledOutput("left", 0)
sleep(0.06)
end
main()
end

function elevator()
if rs.testBundledInput("left", colors.blue) then
req = 1
elseif rs.testBundledInput("left", colors.red) then
req = 2
elseif rs.testBundledInput("left", colors.green) then
req = 3
elseif rs.testBundledInput("left", colors.purple) then
req = 4
elseif rs.testBundledInput("left", colors.orange) then
req = 5
elseif rs.testBundledInput("left", colors.gray) then
req = 6
elseif rs.testBundledInput("left", colors.brown) then
req = 7
end

if rs.testBundledInput("left", colors.lightblue) then
cur = 1
elseif rs.testBundledInput("left", colors.pink) then
cur = 2
elseif rs.testBundledInput("left", colors.lime) then
cur = 3
elseif rs.testBundledInput("left", colors.magenta) then
cur = 4
elseif rs.testBundledInput("left", colors.yellow) then
cur = 5
elseif rs.testBundledInput("left", colors.lightgray) then
cur = 6
elseif rs.testBundledInput("left", colors.cyan) then
cur = 7
end

if cur < req then
up()
elseif cur > req then
down()
end
main()
end

function main()
while true do
os.pullEvent("redstone")
elevator()
end
end