C#

class Base
{
   public static void F() {}
}
class Derived: Base
{
   new private static void F() {}   // Hides Base.F in Derived only
}
class MoreDerived: Derived
{
   static void G() { F(); }         // Invokes Base.F
}

"In the example above, the declaration of F in Derived hides the F that was inherited from Base, but since the new F in Derived has private access, its scope does not extend to MoreDerived. Thus, the call F() in MoreDerived.G is valid and will invoke Base.F."

public class SomeClass
{
    private bool HideThis;

    public SomeClass(int someInt, bool hideThis = false)
    {
         HideThis = hideThis;
         HideThat = hideThat; 
    }

    public void Method1(int someint)
    {
        if(HideThis) return; // or throw error ?

        // whatever
    }
}

if ((MyObject is INotifyCollectionChanged)&& (MyObject is INotifyCollectionChanged))
        Console.WriteLine("This object implements both INotifyPropertyChanged and INotifyCollectionChanged");

if (!(MyObject is INotifyCollectionChanged) && (MyObject is INotifyCollectionChanged))
    Console.WriteLine("This object implements only INotifyPropertyChanged");

public static IObservable<EventPattern<PropertyChangedEventArgs>> Observes<TSource>(this TSource MyObject) where TSource : INotifyPropertyChanged
{
    return null;
}

public static IObservable<EventPattern<PropertyChangedEventArgs>> Observes<TSource>(this TSource MyObject) where TSource : INotifyCollectionChanged
{
    return null;
}