write a go solution for Description:
Nastia has an unweighted tree with n vertices and wants to play with it!

The girl will perform the following operation with her tree, as long as she needs:

1. Remove any existing edge.
2. Add an edge between any pair of vertices.

What is the minimum number of operations Nastia needs to get a bamboo from a tree? A bamboo is a tree in which no node has a degree greater than 2.

Input Format:
The first line contains a single integer t (1<=t<=10,000) — the number of test cases.

The first line of each test case contains a single integer n (2<=n<=10^5) — the number of vertices in the tree.

Next n-1 lines of each test cases describe the edges of the tree in form a_i, b_i (1<=a_i,b_i<=n, a_ineqb_i).

It's guaranteed the given graph is a tree and the sum of n in one test doesn't exceed 2*10^5.

Output Format:
For each test case in the first line print a single integer k — the minimum number of operations required to obtain a bamboo from the initial tree.

In the next k lines print 4 integers x_1, y_1, x_2, y_2 (1<=x_1,y_1,x_2,y_2<=n, x_1neqy_1, x_2neqy_2) — this way you remove the edge (x_1,y_1) and add an undirected edge (x_2,y_2).

Note that the edge (x_1,y_1) must be present in the graph at the moment of removing.

Note:
Note the graph can be unconnected after a certain operation.

Consider the first test case of the example:. Output only the code with no comments, explanation, or additional text.