destwofe

pragma solidity ^0.4.17;

/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;

destwofe

pragma solidity 0.4.18;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;