How to detect if seat is occupied or not?

-- Server Script

local Players = game:GetService("Players") 

Players.PlayerAdded:Connect(function(Player) -- When a player joins
   Player.CharacterAdded:Connect(function(Character) -- When the player spawns
   local Humanoid = Character.Humanoid -- Retrieving the humanoid to get the SeatPart prop

    Humanoid:GetPropertyChangedSignal('SeatPart'):Connect(function() -- When the SeatPart prop changes
     if not Humanoid.SeatPart then 
         print('Player left seat') 
        else 
         print('Player sat')
       end
     end)
   end)
end)

Hope this helps. Anything else you need make sure to ask me.