#include <bits/stdc++.h>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fod(i,a,b) for(int i=a;i>=b;i--)
#define me0(a) memset(a,0,sizeof(a))
#define me1(a) memset(a,-1,sizeof(a))
#define op freopen("in.txt", "r", stdin)
#define pii pair<int,int>
#define mp(x,y) make_pair(x,y)
using namespace std;
const int INF = 0x3f3f3f3f;
typedef unsigned long long ULL;
typedef long long LL;
void read(int& val) { int x = 0; int bz = 1; char c; for (c = getchar(); (c<'0' || c>'9') && c != '-'; c = getchar()); if (c == '-') { bz = -1; c = getchar(); }for (; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + c - 48; val = x * bz; }
const int mod=1e9+7;
const int maxn=1e6+10;

LL ksm(LL a,LL b){
    LL res=1;
    while(b){
        if(b&1) res = res*a%mod;
        a=a*a%mod;b>>=1;
    }
    return res;
}

int a[100];
int main(){
//    op;
    int t;read(t);
    while(t--){
        int n;read(n);
        read(a[1]);
        LL ans=0;
        ans=a[1]*ksm(2,mod-2)%mod;
        fo(i,2,n){
            read(a[i]);
            ans+=(a[i]-a[i-1])*ksm(4,mod-2)%mod;
            ans%=mod;
        }
        printf("%lld\n",ans);
    }

    return 0;
}