OnTimerEndHandler():void=
The issue with your code is that the function is missing a return type. If the function doesn’t return any value, you need to specify void as the return type. This tells the compiler that the function won’t produce a return value. Alternatively, if the function is supposed to return something (like an integer, a string, etc.), you should explicitly define the appropriate return type.
Additionally, if your function requires parameters, you need to specify them within the parentheses.