C# : How to declare Async method in Interface

We can not declare Async method in interface or it's not needed as Async is code marker for compiler it has no relation with overriding feature. If we want to declare Async methods in Interface we need to set return type of method to Task/Task also void method of interface can be implemented as Async. See below example :(Methods implemented in code are not providing any meaningful functionality,it's just to check/show use of Async from interface.)