func: function uint2str(uint i) internal pure returns (string){
      if (i == 0) return "0";
      uint j = i;
      uint length;
      while (j != 0){
          length++;
          j /= 10;
      }
      bytes memory bstr = new bytes(length);
      uint k = length - 1;
      while (i != 0){
          bstr[k--] = byte(48 + i % 10);
          i /= 10;
      }
      return string(bstr);
  }