In a world where people emit light like light bulbs, Jyoti and Farzan are standing in a completely dark room. When Jyoti turns her light on, she can see Farzan clearly, but when she turns her light off, Farzan's light does not come on automatically. How can Jyoti ensure that she can also see Farzan clearly when her light is off?

Respond very briefly.
Jyoti should ask Farzan to turn his light on before she turns hers off. Since people in this world can emit light, if Farzan turns his light on while Jyoti's light is still on, both will be illuminated. Then, when Jyoti turns her light off, assuming Farzan's light remains on, she will still be able to see him clearly thanks to the light he emits. This solution relies on Farzan being in control of his own light emission and will work as long as his light is active when Jyoti's is not.