#include <stdio.h>
#include <string.h>
#define MN 100000
typedef long long LL;
const int mod=1000000007;

int qpow(LL bsc,int x){
    LL ret=1;
    while(x){
        if(x&1) ret=(ret*bsc)%mod;
        bsc=(bsc*bsc)%mod;
        x>>=1;
    }
    return ret;
}

int inv[MN+5];

void initialize(){
    for(int i=1;i<=MN;i++)
        inv[i] = qpow(i,mod-2);
}

int n,m;
int rn,hd[MN+5],to[MN*2+5],nxt[MN*2+5],sz[MN+5];
int normal[MN+5],error[MN+5];

struct path{
    int cnt,a[MN+5];
    bool fixed;
    void clear(){
        cnt = 0;
        fixed = false;
    }
    void push(int x){
        if(fixed) return;
        a[++cnt] = x;
    }
    void pop(){
        if(fixed) return;
        --cnt;
    }
}p;

void _add(int u,int v){
    to[rn]=v;
    nxt[rn]=hd[u];
    hd[u]=rn++;
}

void add(int u,int v){
    _add(u,v),_add(v,u);
    sz[u]++,sz[v]++;
}

void dfs(int u,int f){
    p.push(u);
    if(u==m) p.fixed=true;
    normal[u] = inv[sz[u]];
    if(u==1){
        error[u] = (1ll*(sz[u]-1)*inv[sz[u]])%mod;
        error[u] = (1ll*error[u]*inv[sz[u]-1])%mod;
    }else{
        error[u] = (1ll*(sz[u]-2)*inv[sz[u]])%mod;
        error[u] = (1ll*error[u]*inv[sz[u]-1])%mod;
    }
    for(int i=hd[u];~i;i=nxt[i]){
        if(to[i]==f) continue;
        dfs(to[i],u);
    }
    p.pop();
}

void solve(){
    memset(hd,0xff,sizeof(hd)),rn=0;
    memset(sz,0,sizeof(sz));
    p.clear();
    scanf("%d%d",&n,&m);
    if(n==1){
        puts("1");
        return;
    }
    for(int i=2,u,v;i<=n;i++){
        scanf("%d%d",&u,&v);
        add(u,v);
    }
    dfs(1,0);
    LL ans=0,tans=1;
    for(int i=1;i<p.cnt;i++)
        tans = (tans*normal[p.a[i]])%mod;
    ans = (ans+tans)%mod;
    for(int i=1;i<p.cnt;i++){
        LL ttans = (tans*sz[p.a[i]])%mod;
        ans = (ans+ttans*error[p.a[i]])%mod;
    }
    printf("%lld\n",ans);
}

int main(){
    initialize();
    int T; scanf("%d",&T);
    while(T--) solve();
}