code: function(oldItem, newItem) {
        if(data.operations) {
          for(var i = 0; i < data.operations.length; i++) {
            var operation = data.operations[i];
            if(newItem && newItem[operation.field] !== undefined || oldItem && oldItem[operation.field] !== undefined) {
              opsToolbox[operation.operation].recompute(operations[operation.field], operation, oldItem, newItem);
            }
          }
        }
      }
docs: PRIVATE Methods Recompute the operations results