This is the difference between logical and colloquial use of “or”. If I ask you for a candy that is “not a red candy OR not a green candy”, you can give me literally any candy. Even a green candy meets the “not a red” candy criterion, and the “OR” means you only have to meet one criterion.
But if I ask for a candy that is “not a red candy AND not a green candy”, the “AND” means you have to meet both criteria, so you can’t give me red or green candies 😉
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