Chat gui I made ROBLOX

clone = script.Parent.Default:Clone()

frontsize = 30
buffer = 5
lines = 10

linesize = fontsize + buffer * 2
script.Parent.Size = UDim2.new(0.3, 0, 0, linesize * lines)
script.Parent.Default.Position = UDim2.new(0, 0, 0, linesize * lines - linesize)
script.Parent.Default.FontSize = "Size"..fontsize
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ranks = {       [1] = "Enlist",
                        [2] = "Private",
                        [3] = "Corporal",
                        [4] = "Sergeant",
                        [5] = "Staff Sergeant",
                        [6] = "First Sergeant",
                        [7] = "Sergeant Major",
                        [8] = "Warrant Officer",
                        [9] = "Second Lieutenant",
                        [10] = "First Lieutenant",
                        [11] = "CiT",
                        [12] = "DP",
                        [12+1] = "Captain",
                        [13+1] = "Major",
                        [14+1] = "Colonel",
                        [15+1] = "Major General",
                        [16+1] = "Lieutenant General",
                        [17+1] = "General",
                        [18+1] = "Commander"
}

function shiftup()
        for _, a in pairs(script.Parent:GetChildren()) do
                if a.Name == "Chat" then
                        shared[a].True = shared[a].True + UDim2.new(0, 0, 0, -linesize)
                        a:TweenPosition(shared[a].True, "Out", "Quad", 0.157, true)
                end
        end
end
function Chat(msg, plr, rankoverride)
        shiftup()
        local text = clone:Clone()
        text.Visible = true
        text.Text = msg
        text.Name = "Chat"
        if plr:IsInGroup(226584) or rankoverride then
                if not rankoverride then
                        local rank = Player:GetRankInGroup(226584)
                else
                        rank = rankoverride
                end
                text.Text = "["..ranks[rank].."] "..plr.Name..": "..text.Text
                if rank >= 13 then
                        text.TextColor3 = Color3.new(0, 0, 127/225)
                else
                        text.TextColor3 = Color3.new(28/225, 43/225, 1)
                end
        else
                text.Text = "[Visitor] "..plr.Name..": "..text.Text
        end
        text.Position = text.Position + UDim2.new(0, 0, 0, linesize)
        text.Parent = script.Parent
        text:TweenPosition(UDim2.new(0, 0, 0, linesize * lines - linesize), "Out", "Quad", 0.157, true)
        shared[text] = {}
        shared[text].True = UDim2.new(0, 0, 0, linesize * lines - linesize)
        Lines = text.TextBounds.Y / fontsize --18 is the font size
        for i = 1, Lines - 1 do
                shiftup()
        end
        text.Size = UDim2.new(1, 0, 0, linesize * Lines)
        game:GetService("Debris"):AddItem(text, 60)
end

game.Players.PlayerAdded:connect(function (plr)
        plr.Chatted:connect(function (m)
                Chat(m, plr)
        end)
end)

for _, plr in pairs(game.Players:GetChildren()) do
        plr.Chatted:connect(function (m)
                Chat(m, plr)
        end)
end

_G.chat = Chat