Write simple python/java program and also explain the logic because i am crying so much and not able to understand.

THE VALUE OF A WEIGHTED TREE

You are given a weighted undirected tree with N nodes. Every edge has a weight associated with it.

You are required to find the value of (i=1 to N-1) (j=i+1 to N) F(i,j) function where F(i,j) denotes the sum of weights of edges on a simple path between node i and j.

Input format:

• The first line contains an integer T denoting the number of test cases.
• The first line of each test case contains an integer N denoting the number of nodes in the tree.
• Next N-1 lines contain three space-separated integers u v w denoting an edge between u and v with weight w.

Output format:

For each test case, print the value of function modulo 10^9 + 7 in a new line.