         }
     }
     
-    override var isExecuting: Bool {
+    override open var isExecuting: Bool {
         return _executing
     }
     


import Foundation

class ConcurrentOperation: Operation
{
    override var isAsynchronous: Bool {
        return true
    }
    

        }
    }
    
    override open var isFinished: Bool {
        return _finished
    }
    
    override open func start()
    {
        _executing = true
        execute()
    }
    
    open func execute()
    {
        // Execute your async task here.
    }
    
    open func finish()
    {
        _executing = false
        _finished = true
