func: function __callback(bytes32 myid, string memory result, bytes memory proof) public {
          if (msg.sender != oraclize_cbAddress()) revert();
          require (pendingQueries[myid] == true);
          proof;
          emit NewKrakenPriceTicker(result);
          uint USD = parseInt(result);
          uint tokenPriceInWei = (1 ether / USD) / 100; 
          _rate = 1 ether / tokenPriceInWei;
          updatePrice();
          delete pendingQueries[myid];
      }