example 2

Neetcoin-2.sol

pragma solidity ^0.8.9;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

// https://solidity-by-example.org/sending-ether/

contract Neetcoin is ERC20, Ownable {
    constructor(string memory name_, string memory symbol_) ERC20(name_, symbol_) public {}
    
      function mint(address account, uint256 amount) public onlyOwner {
        _mint(account, amount);
    }
    
      fallback() external payable {
        sell(msg.sender, msg.value);
      }
        
      function sell(address whoToSend, uint256 ntcToMint) payable public {
      address owner_ = owner();
      
      Neetcoin.mint(whoToSend, ntcToMint);
      bool sent = owner_.send(ntcToMint);
      require(sent, "Failed to send Ether");
    }
   }