Text output and hrly coal production 3.1

rednet.open("left")
mon = peripheral.wrap("right")

local total_counted = 0
local counted_hour = 0
local old_total_counted = 0
local lst_of_counted = {}
local lst_for_graph = {}
local cycle = 0


function sum(t)
    local sum = 0
    for k,v in pairs(t) do
        sum = sum + v
    end
    return sum
end

function what_length(t)
    local lengthNum = 0

    for k, v in pairs(t) do -- for every key in the table with a corresponding non-nil value
        lengthNum = lengthNum + 1
    end
    return lengthNum
end

function draw_square(i,j) --i,j are the cursor pos where the block is supposed to be placed.
    i = tonumber(i)
    j = tonumber(j)
    mon.setBackgroundColor(colors.green)
    mon.setCursorPos(i,j)
    mon.write(" ")
    mon.setBackgroundColor(colors.black) end --removed the return

function draw_graph(k) --k should be lst_of_counted
    local counter = 0
    local i = 1
    counter = what_length(lst_for_graph) + 1
    for x=1,50,1 do
        counter = counter - 1
        i = i + 1
        if i > 49 then
           i = 49 end
        if k[counter] == nil then
            return
        elseif counter == 0 then
            return
        elseif k[counter] > 125 then
            for a=18,10,-1 do --draw a 8 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 109 then
            for a=18,11,-1 do --draw a 7 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 93 then
            for a=18,12,-1 do --draw a 6 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 78 then
            for a=18,13,-1 do --draw a 5 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 62 then
            for a=18,14,-1 do --draw a 4 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 46 then
            for a=18,15,-1 do --draw a 3 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] > 31 then
            for a=18,16,-1 do --draw a 2 block high green bar
                draw_square(i,a)
                sleep(0.1) end
        elseif k[counter] < 32 then
            for a=18,17,-1 do --draw a 1 block high green bar
                draw_square(i,a)
                sleep(0.1) end
             end
    end
end

while true do

    local currently_counted = 0

    x,y,z = rednet.receive()

    old_total_counted = total_counted
    cycle = cycle+1
    total_counted = y
    currently_counted = y - old_total_counted
    table.insert(lst_of_counted,currently_counted)
    table.insert(lst_for_graph,currently_counted)

    if cycle > 20 then
        table.remove(lst_of_counted, 1)
        --delete last item of table and then sum together all
        counted_hour = 0
        counted_hour = sum(lst_of_counted)
        end

    if cycle > 50 then
        table.remove(lst_for_graph, 1)
        end

    total_counted = tostring(tonumber(total_counted))
    counted_hour = tostring(tonumber(counted_hour))

    mon.clear()
    draw_graph(lst_for_graph)
    mon.setTextColor(colors.white)
    --Mark the graph
    mon.setCursorPos(1,9)
    mon.write("130")
    mon.setCursorPos(2,19)
    mon.write("3")
    mon.setCursorPos(10.5,19)
    mon.write("36")
    mon.setCursorPos(24,19)
    mon.write("72")
    mon.setCursorPos(37.5,19)
    mon.write("108")
    mon.setCursorPos(48,19)
    mon.write("144")
    sleep(0.1)
    mon.setCursorPos(1,1)
    mon.write("+------------------------------------------------+")
    mon.setCursorPos(1,3)
    mon.write("We have produced a total of ")
    mon.write(total_counted)
    mon.write(" pieces of coal!")
    mon.setCursorPos(1,5)
    mon.write(total_counted)
    mon.write(" makes ")
    mon.write(tostring(tonumber(math.floor(total_counted/64))))
    mon.write(" stacks of coal! ")
    if cycle > 10 then
        mon.setCursorPos(1,7)
        mon.write("Last hour ")
        mon.write(counted_hour)
        mon.write(" pieces of coal were produced!")
        mon.setCursorPos(1,20)
        mon.write("+------------------------------------------------+")
    else
        mon.setCursorPos(1,7)
        mon.write("Last hour [N/A] pieces of coal were produced!")
        mon.setCursorPos(1,20)
        mon.write("+------------------------------------------------+")
    end
end