         }
     }
     
-    override func start() {
+    override public func start() {
         if self.cancelled {
             self.isFinished = true
         }

        }
    }
    
    override var executing: Bool {
        return self.isExecuting
    }
    
    override var finished: Bool {
        return self.isFinished
    }
    

        }
    }
    
    override public func main() {
        if let operationBlock = self.operationBlock {
            operationBlock()
        }
