description: A tree is an undirected connected graph without cycles.
  
  You are given a tree of n vertices. Find the number of ways to choose exactly k vertices in this tree (i. e. a k-element subset of vertices) so that all pairwise distances between the selected vertices are equal (in other words, there exists an integer c such that for all u, v (u ≠ v, u, v are in selected vertices) d_{u,v}=c, where d_{u,v} is the distance from u to v).
  
  Since the answer may be very large, you need to output it modulo 10^9 + 7.
  
  Input
  
  The first line contains one integer t (1 ≤ t ≤ 10) — the number of test cases. Then t test cases follow.
  
  Each test case is preceded by an empty line.
  
  Each test case consists of several lines. The first line of the test case contains two integers n and k (2 ≤ k ≤ n ≤ 100) — the number of vertices in the tree and the number of vertices to be selected, respectively. Then n - 1 lines follow, each of them contains two integers u and v (1 ≤ u, v ≤ n, u ≠ v) which describe a pair of vertices connected by an edge. It is guaranteed that the given graph is a tree and has no loops or multiple edges.
  
  Output
  
  For each test case output in a separate line a single integer — the number of ways to select exactly k vertices so that for all pairs of selected vertices the distances between the vertices in the pairs are equal, modulo 10^9 + 7 (in other words, print the remainder when divided by 1000000007).
  
  Example
  
  Input
  
  
  3
  
  4 2
  1 2
  2 3
  2 4
  
  3 3
  1 2
  2 3
  
  5 3
  1 2
  2 3
  2 4
  4 5
  
  
  Output
  
  
  6
  0
  1
solution: import java.util.*;
  import java.io.*;
  
  public class Main {
      public static void main(String args[]) {new Main().run();}
  
      FastReader in = new FastReader();
      PrintWriter out = new PrintWriter(System.out);
      void run() {
          for(int q=ni();q>0;q--){
              work();
          }
          out.flush();
      }
      long mod=1000000007;
      long gcd(long a,long b) {
          return a==0?b:gcd(b%a,a);
      }
      ArrayList<Integer>[] graph;
      long ret;
      int n,k;
      void work() {
          n=ni();
          k=ni();
          ret=0;
          graph=ng(n,n-1);
          if(k==2){
              out.println((long)n*(n-1)/2%mod);
              return;
          }
          for(int i=0;i<n;i++){
              find(i);
          }
          out.println(ret);
      }
  
      int[][] dp;
      private void find(int node) {
          dp=new int[n][n];
          dfs(node,new boolean[n]);
          for(int i=1;i<=n;i++){
              int c=0;
              int[] rec=new int[n+1];
              for(int nn:graph[node]){
                  if(dp[nn][i-1]>0){
                      c++;
                      rec[c]=dp[nn][i-1];
                  }
              }
              if(c<k){
                  break;
              }
              long[][] dp2=new long[c+1][k+1];
              for(int j=0;j<=c;j++){
                  dp2[j][0]=1;
              }
              for(int j=1;j<=c;j++){
                  for(int p=1;p<=k;p++){
                      dp2[j][p]=(dp2[j-1][p]+dp2[j-1][p-1]*rec[j]%mod)%mod;
                  }
              }
              ret=(ret+dp2[c][k])%mod;
          }
      }
  
      private void dfs(int node,boolean[] vis) {
          vis[node]=true;
          for(int nn:graph[node]){
              if(!vis[nn]){
                  dfs(nn,vis);
                  for(int i=1;i<n;i++){
                      dp[node][i]+=dp[nn][i-1];
                  }
              }
          }
          dp[node][0]=1;
      }
  
      //input
      @SuppressWarnings("unused")
      private ArrayList<Integer>[] ng(int n, int m) {
          ArrayList<Integer>[] graph=(ArrayList<Integer>[])new ArrayList[n];
          for(int i=0;i<n;i++) {
              graph[i]=new ArrayList<>();
          }
          for(int i=1;i<=m;i++) {
              int s=in.nextInt()-1,e=in.nextInt()-1;
              graph[s].add(e);
              graph[e].add(s);
          }
          return graph;
      }
  
      private ArrayList<long[]>[] ngw(int n, int m) {
          ArrayList<long[]>[] graph=(ArrayList<long[]>[])new ArrayList[n];
          for(int i=0;i<n;i++) {
              graph[i]=new ArrayList<>();
          }
          for(int i=1;i<=m;i++) {
              long s=in.nextLong()-1,e=in.nextLong()-1,w=in.nextLong();
              graph[(int)s].add(new long[] {e,w});
              graph[(int)e].add(new long[] {s,w});
          }
          return graph;
      }
  
      private int ni() {
          return in.nextInt();
      }
  
      private long nl() {
          return in.nextLong();
      }
      private double nd() {
          return in.nextDouble();
      }
      private String ns() {
          return in.next();
      }
  
      private long[] na(int n) {
          long[] A=new long[n];
          for(int i=0;i<n;i++) {
              A[i]=in.nextLong();
          }
          return A;
      }
  
      private int[] nia(int n) {
          int[] A=new int[n];
          for(int i=0;i<n;i++) {
              A[i]=in.nextInt();
          }
          return A;
      }
  }
  
  class FastReader
  {
      BufferedReader br;
      StringTokenizer st;
      InputStreamReader input;//no buffer
      public FastReader()
      {
          br=new BufferedReader(new InputStreamReader(System.in));
      }
  
      public FastReader(boolean isBuffer)
      {
          if(!isBuffer){
              input=new InputStreamReader(System.in);
          }else{
              br=new BufferedReader(new InputStreamReader(System.in));
          }
      }
  
      public boolean hasNext(){
          try{
              String s=br.readLine();
              if(s==null){
                  return  false;
              }
              st=new StringTokenizer(s);
          }catch(IOException e){
              e.printStackTrace();
          }
          return true;
      }
  
      public String next()
      {   
          if(input!=null){
              try {
                  StringBuilder sb=new StringBuilder();
                  int ch=input.read();
                  while(ch=='\n'||ch=='\r'||ch==32){
                      ch=input.read();
                  }
                  while(ch!='\n'&&ch!='\r'&&ch!=32){
                      sb.append((char)ch);
                      ch=input.read();
                  }
                  return sb.toString();
              }catch (Exception e){
                  e.printStackTrace();
              }
          }
          while(st==null || !st.hasMoreElements())//回车，空行情况
          {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
  
      public int nextInt()
      {
          return (int)nextLong();
      }
  
      public long nextLong() {
          try {
              if(input!=null){
                  long ret=0;
                  int b=input.read();
                  while(b<'0'||b>'9'){
                      b=input.read();
                  }
                  while(b>='0'&&b<='9'){
                      ret=ret*10+(b-'0');
                      b=input.read();
                  }
                  return ret;
              }
          }catch (Exception e){
              e.printStackTrace();
          }
          return Long.parseLong(next());
      }
  
      public double nextDouble()
      {
          return Double.parseDouble(next());
      }
  }