Public Overloads Sub Perform( _
   ByVal ioAction As Action(Of Stream) _
) 

public void Perform( 
   Action<Stream> ioAction
)

using (TestStream io = new TestStream())
using (BackgroundWriter wtr = new BackgroundWriter(io))
{
    wtr.Perform(s => s.Write(new byte[100], 0, 100));
    wtr.Flush();
    Assert.AreEqual(100, io.Position);
    Assert.AreEqual(100, io.Length);
}

Using io As New TestStream()
    Using wtr As New BackgroundWriter(io)
        wtr.Perform(Function(s) s.Write(New Byte(100) {}, 0, 100))
        wtr.Flush()
        Assert.AreEqual(100, io.Position)
        Assert.AreEqual(100, io.Length)
    End Using
End Using