gistfile1.txt

contract Ownable {
  address public owner;
  
  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
  
  function Ownable() public {
    owner = msg.sender;
  }
  
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }
  
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }
}