'宣言 Public Overloads Shared Sub AddLevel(Of T)( _ ByVal hierarhyDescriptor As HierarchyDescriptor(Of T), _ ByVal expr As Expression(Of Func(Of T,Object)), _ ByVal levelName As String _ )
public static void AddLevel<T>( HierarchyDescriptor<T> hierarhyDescriptor, Expression<Func<T,object>> expr, string levelName )