write a go solution for Description:
Kamil likes streaming the competitive programming videos. His MeTube channel has recently reached 100 million subscribers. In order to celebrate this, he posted a video with an interesting problem he couldn't solve yet. Can you help him?

You're given a tree — a connected undirected graph consisting of n vertices connected by n-1 edges. The tree is rooted at vertex 1. A vertex u is called an ancestor of v if it lies on the shortest path between the root and v. In particular, a vertex is an ancestor of itself.

Each vertex v is assigned its beauty x_v — a non-negative integer not larger than 10^12. This allows us to define the beauty of a path. Let u be an ancestor of v. Then we define the beauty f(u,v) as the greatest common divisor of the beauties of all vertices on the shortest path between u and v. Formally, if u=t_1,t_2,t_3,...,t_k=v are the vertices on the shortest path between u and v, then f(u,v)=gcd(x_t_1,x_t_2,...,x_t_k). Here, gcd denotes the greatest common divisor of a set of numbers. In particular, f(u,u)=gcd(x_u)=x_u.

Your task is to find the sum

 \sum_{u\text{ is an ancestor of }v} f(u, v). 

As the result might be too large, please output it modulo 10^9+7.

Note that for each y, gcd(0,y)=gcd(y,0)=y. In particular, gcd(0,0)=0.

Input Format:
The first line contains a single integer n (2<=n<=100,000) — the number of vertices in the tree.

The following line contains n integers x_1,x_2,...,x_n (0<=x_i<=10^12). The value x_v denotes the beauty of vertex v.

The following n-1 lines describe the edges of the tree. Each of them contains two integers a,b (1<=a,b<=n, aneqb) — the vertices connected by a single edge.

Output Format:
Output the sum of the beauties on all paths (u,v) such that u is ancestor of v. This sum should be printed modulo 10^9+7.

Note:
The following figure shows all 10 possible paths for which one endpoint is an ancestor of another endpoint. The sum of beauties of all these paths is equal to 42:. Output only the code with no comments, explanation, or additional text.