Chocolate is the first luxury. It has so many things wrapped up in it: Deliciusness in the moment childhood memories and that grin-inducing feeling of getting a reward for being good.
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It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes it was 29 years.