NaN

--Moduke script
return function(a,b)
   local weld = Instance.new("Weld")
   weld.Part0 = a
   weld.Part1 = b
   weld.C0 = a.CFrame:inverse() * b.CFrame
   weld.Parent = a
end

--server script
game.Players.ChildAdded:connect(function(player)
    player.CharacterAdded:connect(function()
        repeat wait() until player.Character
        repeat wait() until player.Character["Left Leg"]
        require(script.ModuleScript(player.Character["Left Leg"], game Workspace.Part))
    end)
end)