Light sticks have pretty limited utility but I keep some around. They're cool and nonflammable so they can't start a fire. They don't need batteries and they keep for quite a while. On the other hand their output is low and the "burn time" is short(ish) depending on your POV. They're inexpensive enough and compact enough that I keep some for the limited range of things they work well for (mostly camping for use as markers).
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman