After scanning a document or a receipt, most of your camera apps work as a nightstand.

When you scan a receipt or document, it tries to take the picture when the lighting is best so it can be cropped as a single image. When you are taking a photo in a dark room, and want the light to turn on for a bunch of seconds, like for a time lapse or a hyperlapse. You can keep the flash on in photo mode, turn your screen brightness all the way up, put the phone in pro mode (Manual Focus/Manual ISO) and put it on a tripod. Then keep the flash and screen on by putting something on the screen to keep the flash and light on. To try this, point the camera at a piece of paper, and then put your finger on the part of the screen where it says the sun/rays of light.