PresaleExample1.md

mapping(address => uint256) amountMintedSoFar;

function presale(bytes calldata _proof) external payable {
        require(totalSupply() < MAX_TOKEN_SUPPLY);
        require(msg.value == PRICE);
        require(validateUser(_proof, msg.sender);
        require(amountMintedSoFar[msg.sender] < MAX_PER_USER);
        
        amountMintedSoFar[msg.sender]++;
        _mint(msg.sender, totalSupply());
}