#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int,int> pii;
#define fir first
#define sec second
#define rep(i,a,b) for (int i = (a) ; i <= (b) ; ++ i)
#define rrp(i,a,b) for (int i = (a) ; i >= (b) ; -- i)
#define gc() getchar()
template <typename tp>
inline void read(tp& x) {
  x = 0; char tmp; bool key = 0;
  for (tmp = gc() ; !isdigit(tmp) ; tmp = gc())
    key = (tmp == '-');
  for ( ; isdigit(tmp) ; tmp = gc())
    x = (x << 3) + (x << 1) + (tmp ^ '0');
  if (key) x = -x;
}
template <typename tp>
inline void ckmn(tp& x,tp y) {
  x = x < y ? x : y;
}
template <typename tp>
inline void ckmx(tp& x,tp y) {
  x = x < y ? y : x;
}

const int MOD = (int)(1e9 + 7);
int power(int a,int b) {
  int ret = 1;
  while (b) {
    if (b&1) ret = (ll)ret * a % MOD;
    a = (ll) a * a % MOD;
    b >>= 1;
  }
  return ret;
}
const int N = 100010;
struct edge {
  int la,b;
} con[N << 1];
int tot, fir[N];
void add_edge(int from,int to) {
  con[++tot] = (edge) {fir[from], to};
  fir[from] = tot;
}
int n, m;
vector<int> vec;
bool dfs(int pos,int fa) {
  if (pos == m) return true;
  bool ret = 0;
  int deg = 0;
  for (int i = fir[pos]; i; i = con[i].la) {
    ++ deg;
    if (con[i].b == fa) continue;
    ret |= dfs(con[i].b, pos);
  }
  if (ret) vec.push_back(deg);
  return ret;
}
void init() {
  vec.clear();
  memset(fir, 0, sizeof fir);
  tot = 0;
}
void solve() {
  int x,y;
  init();
  read(n), read(m);
  rep (i, 1, n-1) {
    read(x), read(y);
    add_edge(x, y), add_edge(y, x);
  }
  dfs(1, 0);
  pii ans(1, 0);
  rep (i, 0, (int)vec.size()-1) {
    int tmp = vec[i];
    x = power(tmp, MOD - 2);
    if (i == (int)vec.size()-1) {
      if (tmp == 1) y = 0;
      else y = power(tmp, MOD - 2);
    }
    else y = (ll)(tmp - 2) * power(tmp, MOD - 2) % MOD * power(tmp - 1, MOD - 2) % MOD;
    ans = pii((ll)ans.fir * x % MOD, ((ll)ans.fir * y + (ll)ans.sec * x) % MOD);
  }
  int tmp = (ans.fir + ans.sec) % MOD;
  printf("%d\n", tmp);
}
int main() {
  int T;
  read(T);
  while (T --)
    solve();
  return 0;
}