#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
using namespace std;

void read(int &x) {
    x = 0; char c = getchar();
    while (c < '0' || c > '9') c = getchar();
    while (c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();    
}

typedef long long ll;

const int N = 1e5 + 100;
const int MOD = 1e9 + 7;

ll rev[N];

ll R(int x) {
    if (rev[x]) return rev[x];
    return rev[x] = (MOD - MOD / x) * R(MOD % x) % MOD;
}

int n, m, tp;
int sta[N], f[N];
vector<int> V[N];

bool dfs(int u, int fa) {
    sta[++tp] = u;
    if (u == m) return true;
    for (int v : V[u]) {
        if (v == fa) continue;
        if (dfs(v, u)) return true;
    }
    tp--;
    return false;
}

int main() {
    //freopen("0.txt", "r", stdin);
    rev[0] = rev[1] = 1;
    int T, a, b;
    read(T);
    while (T--) {
        read(n);  read(m);
        for (int i = 1; i < n; i++) {
            read(a); read(b);
            V[a].push_back(b);
            V[b].push_back(a);
        }
        dfs(1, 0);
        f[tp] = 1;
        for (int i = tp - 1; i > 0; i--) {
            f[i] = R(V[sta[i]].size()) * f[i + 1] % MOD;
        }
        ll res = 1, ans = f[1];
        for (int i = 1; i < tp; i++) {
            if (i == 1) {
                if (V[1].size() > 1)
                    ans = (ans + (V[1].size() - 1) * R(V[1].size()) % MOD * R(V[1].size() - 1) % MOD * f[2]) % MOD;
            }
            else {
                if (V[sta[i]].size() > 2) {
                    ans = (ans + (V[sta[i]].size() - 2) * R(V[sta[i]].size()) % MOD * R(V[sta[i]].size() - 1) % MOD * f[i + 1] % MOD * res) % MOD;
                }
            }
            res = res * R(V[sta[i]].size()) % MOD;
        }
        printf("%lld\n", ans);
        for (int i = 1; i <= n; i++) V[i].clear();
        tp = 0;
    }
    return 0;
}