public static T If<T>(
	this T container,
	string expression,
	AbstractStructure thenContent,
	AbstractStructure elseContent = null
)
where T : AbstractStructure

<ExtensionAttribute>
Public Shared Function If(Of T As AbstractStructure) ( 
	container As T,
	expression As String,
	thenContent As AbstractStructure,
	Optional elseContent As AbstractStructure = Nothing
) As T