The third requirement (“Glitchless”) is important for correctness. We don’t want intermediate states to be observable — if this were possible, then we can end up with invalid states. Consider two neighbouring cells, one that contains a country’s ISO country code (UK, DE, BE, etc), and another that contains the full name of that country. We don’t want to be able to observe the state where the two cells are out-of-sync with each other.
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