请大家帮忙看看这个程序是怎么执行的，谢谢


public void GroupGetChildrenTreeList()
{
GroupObject go = new GroupObject();
Group group = (Group)go.GetById("001G00000152");
IList lst = go.GetChildrenTreeList(group);
}public IList GetChildrenTreeList(Group group) 
{
ArrayList childrenTreeList = new ArrayList();                 //(1)
foreach(Group childGroup in group.SubGroups)                  //(2)
{
childrenTreeList.AddRange(GetChildrenTreeList(childGroup));   //(3)
}
childrenTreeList.Add(group);   //(4)
return childrenTreeList;       //(5)
}GetChildrenTreeList这个函数内部执行怎么是：（1）---（2）---（3）---（4）---(5)---(3)---(2)--(4)---(5)
                                    ---(3)---(2)--(4)---(5)---(3)---(2)--(4)---(5)很奇怪，执行return没跳出？？!!!