What we know so far about the US-Israel attacks and Iran's retaliation
再把硬币翻过来，看看阿拉伯人 (Arabs) 的视角：他们手里握着一张无法反驳的王牌——正统性。
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for example, the regex [a-zA-Z] only cares about two kinds of characters: letters and everything else. so instead of individually taking derivatives for 52 alphabet characters a..z, A..Z, we can conclude from the start that there are only two kinds of characters we care about: letters ([a-zA-Z]) and non-letters ([^a-zA-Z]).