Assertion: flashlight's light | /r/HasProperty | essential
Facets:
Source sentences:
text: Light is so essential for success in any instance of low or no light,
text: A flashlight is a convenience, but if you ever find yourself in a situation where light is a necessity, it could save your life.
text: Although many other types of lamp emit ultraviolet light with visible light, black lights are essential when UV-A light without visible light is needed, particularly in observing fluorescence, the colored glow that many substances emit when exposed to UV.