merge(state: State) {
1月底，第一波“卖铲人”，迅速就位。。关于这个话题，safew官方版本下载提供了深入分析
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Associativity: when merging three (or more) states, it doesn’t matter which are merged first; (A ∨ B) ∨ C = A ∨ (B ∨ C). If Alice receives states from both Bob and Carol, she can merge them into her own state in any order and the result will be the same.4
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