1:  'Definition
   2:  Imports System.Runtime.ComplierServices
   3:   
   4:  <Extension()>
   5:  Public Sub Add(ByVal BaseCriteria As CriteriaOperator, ByVal AdditionalCriteria As CriteriaOperator, Optional ByVal JoinType As GroupOperatorType = GroupOperatorType.And)
   6:      If AdditionalCriteria IsNot Nothing Then
   7:          If BaseCriteria Is Nothing Then
   8:              BaseCriteria = AdditionalCriteria
   9:          Else
  10:              BaseCriteria = New GroupOperator(JoinType, BaseCriteria, AdditionalCriteria)
  11:          End If
  12:      End If
  13:  End Sub
  14:   
  15:  'Usage
  16:  Imports <TheNamespaceYourExtensionMethodIsDefined>
  17:   
  18:  Public Sub DoSomething()
  19:      Dim SecurityCriteria As CriteriaOperator = Nothing
  20:      SecurityCriteria.Add(New BinaryOperator("MyField", "Value1"))
  21:      SecurityCriteria.Add(New BinaryOperator("SomeOtherField", "Value2"))
  22:      Debug.Print(SecurityCriteria.ToString())
  23:      'Returns [MyField] = 'Value1' AND [SomeOtherField] = 'Value2'
  24:  End Sub