Imports System

Public Module Module1

    Public Sub Test()

        Test(Nothing)

    End Sub

    Public Sub Test(ByRef bla As String)

        bla = "test bla"

    End Sub

    Public Sub Main()

        Dim tst As String

        Test()

        'Test(tst)

        Console.WriteLine(tst)

        Console.WriteLine("Done")

    End Sub

End Module