chapter23-code-5

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Thu Mar 30 2023 11:35:40 GMT+0000 (Coordinated Universal Time)

Saved by @RareSkills 

contract ExampleContract {

	// defaults to zero
	uint256 private calledAt;

	function callMeFirst() external {
		calledAt = block.number;
	}

	function callMeSecond() external {
		require(calledAt != 0 && block.number > calledAt, "callMeFirst() not called");
	}
}
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