public class CollectionValueBase[T]
{
  public virtual ToArray() :   array [T]
  {
     null;
  }
}

public class CollectionBase[T]: CollectionValueBase[T]
{
}

public class SequencedBase[T]: CollectionBase[T]
{
}

public class ArrayBase[T]: SequencedBase[T]
{
  public override ToArray() :   array [T]
  {
     null;
  }
}

class X
{
  static Main () :  void
  { }
}
/*
BEGIN-OUTPUT
END-OUTPUT
*/