Has it died and its owner brought it to the cemetery for burial? ( here in Australia we often say when machines/appliances break down that they have 'died' 🙁)
Or, were some relatives of a 'resident' of the cemetery concerned that their loved one might be cold?
If so, where will they plug it in?
Or as my brother in law quipped, 'What sort of headstone, would suit a heater?'.
Just shows you can find something that makes you smile in the most unexpected places. 😉