I have created an ultrasonic sensor which is mounted into a sewer cover and measures the amount of capacity left in the sewer tank. This sensor is based on ESPhome. This sensor gets power supply only a couple hours a day and is offline for the rest of the day. When offline, it shows up as ‘unavailable’ and displays no data on the history graph. Is there a way to make HA display the last know value instead of ‘unavailable’ (e.g. the measurement value from when the sensor has been online for the last time)?