'Ask the user which add-in they would like to use.
Dim selectedToken As AddInToken = ChooseAddIn(tokens)
'Activate the selected AddInToken in a new
'application domain with the Internet trust level.
Dim CalcAddIn As Calculator = selectedToken.Activate(Of Calculator)(AddInSecurityLevel.Internet)
'Run the add-in using a custom method.
RunCalculator(CalcAddIn)

' Method to select a token by 
' enumeratng the AddInToken collection.

Private Shared Function ChooseAddIn(ByVal tokens As System.Collections.ObjectModel.Collection(Of AddInToken)) As AddInToken
    If (tokens.Count = 0) Then
        Console.WriteLine("No add-ins are available")
        Return Nothing
    End If
    Console.WriteLine("Available add-ins: ")
    ' Show the token properties for each token 
    ' in the AddInToken collection (tokens),
    ' preceded by the add-in number in [] brackets.

    Dim tokNumber As Integer = 1
    For Each tok As AddInToken In tokens
        Console.WriteLine(vbTab & "{0}: {1} - {2}" & _
                vbLf & vbTab & "{3}" & _
                vbLf & vbTab & "{4}" & _
                vbLf & vbTab & "{5} - {6}", _
                tokNumber.ToString, tok.Name, _
                tok.AddInFullName, tok.AssemblyName, _
                tok.Description, tok.Version, tok.Publisher)
        tokNumber = tokNumber + 1
    Next
    Console.WriteLine("Which calculator do you want to use?")
    Dim line As String = Console.ReadLine
    Dim selection As Integer
    If Int32.TryParse(line, selection) Then
        If (selection <= tokens.Count) Then
            Return tokens((selection - 1))
        End If
    End If
    Console.WriteLine("Invalid selection: {0}. Please choose again.", line)
    Return ChooseAddIn(tokens)

End Function