How to get Item from specified Chest-slot?

--[[

.. Turtle file for Reactor-Control .. by meigrafd

--]]


---[[ CONFIG - START ]]


-- Modem channel to listen for commands from Computer.
local ModemChannel = 32768 -- Broadcast channel.

-- Maximum loop time (default: 0.5s)
local loopT=0.5

-- Chest Inventory Sides for which Items. Only valid sides: left, right, back, up
-- NOTE: Fastest for Coolant will be "up"
-- (wireless modem is always on the left, but no problem)
-- put a chest below the turtle as trash where it drops all it takes outa reactor
chestCoolant = "up"
chestUran = "back"
chestTrash = "down"
chestReactor = "front"  --turtle must be placed so this fits!


---[[ CONFIG - END ]]


---[[ functions ]]


function getDeviceSide(deviceType)
	-- loop through all the sides
	for i,side in pairs(rs.getSides()) do
		if (peripheral.isPresent(side)) then
			-- Yup, there is something on this side
			if (peripheral.getType(side) == string.lower(deviceType)) then
				-- Yes, this is the device type we need, so return the side
				return side;
			end
		end
	end
	--nothing found, return nil
	return nil;
end

function changeReactorState(state)
	print("Changing Reactor State to: "..state)
	if state == "off" then
		rs.setOutput(chestReactor, false)
	else
		rs.setOutput(chestReactor, true)
	end
end

function turn(side)
	if side == "left" then
		turtle.turnLeft()
	elseif side == "right" then
		turtle.turnRight()
	elseif side == "front" then
		turtle.turnRight()
		turtle.turnRight()
	elseif side == "back" then
		turtle.turnLeft()
		turtle.turnLeft()
	end
end

-- verify reactor in front
function verifyReactor()
	local success, detect = turtle.inspect()
	if string.find(string.lower(detect.name), "reactor") then
		return true
	else
		return false
	end
end

function Coolant()
	if chestCoolant == "up" then
		if not turtle.suckUp(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
	elseif chestCoolant == "down" then
		if not turtle.suckDown(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
	else
		turn(chestCoolant)
		if not turtle.suck(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
		turn(chestReactor)
	end
	-- verify reactor in front
	while verifyReactor() == false do
		turn('left')
	end
	success = turtle.drop()
	commandsexecdCount = commandsexecdCount + 1
end

function Uran()
	if chestUran == "up" then
		if not turtle.suckUp(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
	elseif chestUran == "down" then
		if not turtle.suckDown(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
	else
		turn(chestUran)
		if not turtle.suck(1) then
			print("WARNING: can't pick up the item!")
			changeReactorState('off')
		end
		turn(chestReactor)
	end
	-- verify reactor in front
	while verifyReactor() == false do
		turn('left')
	end
	success = turtle.drop()
	commandsexecdCount = commandsexecdCount + 1
end


--[[ Internal values ]]


local version = 0.2
turtle.select(1)
commandsexecdCount=0
w,h = term.getSize()
sleep(2) -- wait for 2s


--[[ Main program ]]


term.clear()
-- detect Modem
print('Connecting to modem...')
sleep(0.5)
side = getDeviceSide("modem")
if side == nil then
	error('Error: Could not connect to Modem!')
else
	myModem = peripheral.wrap(side)
	myModem.open(ModemChannel)
	if myModem.isWireless() then
		print('success  (wireless)')
	else
		print('success')
	end
	sleep(0.5)
end
sleep(3)
term.clear()

--changeReactorState('on')


-- Receive messages Event loop
while true do
	tID = os.startTimer(loopT) -- Wait for loopT secounds.
	repeat
		local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent()
		if event == "modem_message" then
			local Slot = message.slot
			local Item = message.item
			print('('..commandsexecdCount..') slot#'..Slot..' -> '..Item)
			if string.find(string.lower(Item), "coolant") then
				Coolant()
			elseif string.find(string.lower(Item), "uran") then
				Uran()
			else
				print('ERROR: received unknown Item "'..Item..'"')
			end
		end
	-- exit repeat loop on timer event
	until (event == "timer" and modemSide == tID)
end