编写算法完成下列操作：无重复地输出以孩子兄弟链表存储的树T中所有的边（这里的边是指树T本身的分支，而不是孩子兄弟链表所形成的二叉树的分支）。输出的形式为（k1, k2）, ..., (ki, kj), ..., 其中，ki和kj为树结点中的结点标识。-Write an algorithm to do the following: no repeat output to all sides in children the brothers linked list storage tree T (where the edge is the branch of the tree T, rather than the child brother chain formed binary tree branch). The output in the form of the (k1, k2), ..., (ki, kj), ..., wherein Ki and kj tree node in the node identification.