Sub Main()
    Dim ac As New AppleCart({New Apple(), New Apple()})
    For Each a In ac.Fruits
        a.Rot() ' prints "The apple is rotten!"
    Next
    Console.Read()
End Sub

Public Class Fruit
    Public Overridable Sub Rot()
        Console.WriteLine("The fruit is rotten!")
    End Sub
End Class

Public Class Apple
    Inherits Fruit
    Public Overrides Sub Rot()
        Console.WriteLine("The apple is rotten!")
    End Sub
End Class

Public Class FruitStand(Of T As Fruit)
    Private _fruits As List(Of T)
    Public ReadOnly Property Fruits As IEnumerable(Of T)
        Get
            Return _fruits
        End Get
    End Property
    Public Sub New(fruits As IEnumerable(Of T))
        _fruits = fruits.ToList()
    End Sub
End Class

Public Class AppleCart
    Inherits FruitStand(Of Apple)
    Public Sub New(fruits As IEnumerable(Of Apple))
        MyBase.New(fruits)
    End Sub
End Class