Public Class square
    Private size As Double

    ' constructor
    Public Sub New()
        size = 1
    End Sub

    ' constructor
    Public Sub New(ByVal len As Double)
        size = len
    End Sub

    ' property definitions
    Public Property side()
        Get
            Return size
        End Get
        Set(ByVal Value)
            If Value > 0 Then
                size = Value

            End If

        End Set
    End Property

    Public Function calcArea()
        Dim area As Double
        area = size * size
        Return area
    End Function

End Class