public static void DoChild(object state)
        {
            Console.WriteLine($"child {state} starting");
            Thread.Sleep(2000);
            Console.WriteLine($"Child {state} finished");
        }

        public static void ChildTasks()
        {
            var parent = Task.Factory.StartNew(() =>
            {
                Console.WriteLine("Parent Starts");
                //Child tasks can run independent of the parent or can be attached to parent
                //in the case of independent we can use Run method of task or explicitly state in
                //task creation option
                for(int i=0;i<10; i++)
                {
                    int taskNo = i;
                    Task.Factory.StartNew(
                        (x) => DoChild(x),
                                taskNo,
                                TaskCreationOptions.AttachedToParent);
                }
            });

            parent.Wait();
            Console.WriteLine("Finished Processing. Press a key to end");
            Console.ReadKey();
        }