how to detect TalkBack is active? using Xamarin Forms -Dependency service

I will like to return true or false if TalkBack is active.

public bool IsVoiceOver() {

     AccessibilityManager am = (AccessibilityManager) 
     Context.AccessibilityService;

        var a =  am.IsEnabled;
        if (!a) 
        {
            Console.WriteLine(" DROID voice over   is : " + a);
            return false;
        }
        else 
        {
            Console.WriteLine("DROID voice over  is : " + a);
        return true;
        }
    }

However, "AccessibilityManager" is not working. I guess is a syntax issue not sure.

from how to detect TalkBack is active? using Xamarin Forms -Dependency service