Private Sub btnDisplay_Click(...) Handles btnDisplay.Click

  Dim a, b As String

  txtBox.Clear()

  a = "A"

  b = "B"

  PrintWords(a, b)

  PrintWords(b, a)

End Sub

Private Sub btnKatButton_Click(...) Handles btnKatButton.Click
   txtBox.Text = "This shouldn't say "
   Print("Hello", " World")
   'txtBox.Text will have in it: "This shouldn't say Hello World"
   KatPrint("Hello", " World")
   'txtBox.Text will have in it: "Hello World"
End Sub

Private Sub KatPrint(ByVal first As String, ByVal second As String)
   txtBox.Text = first & second
End Sub

Sub PrintWords(ByVal a As String, ByVal b As String)

  txtBox.Text &= a & b

End Sub