FileStream.Close()

        // Stream used to require that all cleanup logic went into Close(),
        // which was thought up before we invented IDisposable.  However, we
        // need to follow the IDisposable pattern so that users can write
        // sensible subclasses without needing to inspect all their base
        // classes, and without worrying about version brittleness, from a
        // base class switching to the Dispose pattern.  We're moving
        // Stream to the Dispose(bool) pattern - that's where all subclasses
        // should put their cleanup starting in V2.
        public virtual void Close()
        {
            /* These are correct, but we'd have to fix PipeStream & NetworkStream very carefully.
            Contract.Ensures(CanRead == false);
            Contract.Ensures(CanWrite == false);
            Contract.Ensures(CanSeek == false);
            */

            Dispose(true);
            GC.SuppressFinalize(this);
        }