How to express SOS with flashlight

Using Morse code to send SOS distress signal is an international emergency distress mode. This code represents S as "…", that is, three short message numbers; O stands for "-",which means three long signals. The length of a long signal is about three times that of a short message. In this way, SOS can be represented by any signal of "three short, three long and three short". You can use light, such as switching flashlights, miner's lamps, emergency lights, car headlights, indoor lighting or even blocking kerosene lamps, and you can also use sounds, such as whistles, whistles, car horns and even knocking at the door. Every time a group of SOS is sent, pause for a moment before sending the next group.