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Trust.sol

pragma solidity = 0.8.1;

contract Trust {
    struct Kid {
        uint amount;
        uint maturity;
        bool paid;
    }
    
    mapping(address => Kid) public kids;
    
    address public admin;
    
    constructor(){
        admin = msg.sender;
    }
    
    function addKid(address kid, uint timeToMaturity) external payable {
        require(msg.sender == admin, 'only admin');
        require(kids[msg.sender].amount == 0, 'kid already exist');
        
        kids[kid] = Kid(msg.value, block.timestamp + timeToMaturity, false);
    }
    
    function withdraw() external {
        Kid storage kid = kids[msg.sender];
        require(kid.maturity <= block.timestamp, 'too early');
        require(kid.amount > 0, 'only kid can withdraw');
        require(kid.paid == false, 'paid already');
        kid.paid = true;
        payable(msg.sender).transfer(kid.amount);
    }
}