#include <cstdio>

 #include <cstring>

 #include <algorithm>

 #define ll long long

 #define maxn 10000

 #define mod 10000000007

 using namespace std;

 ll a[maxn];

 ll n,k,t;

 ll fMul(ll a, ll b) {

     ll t = , y = a;

     while(b) {

         if(b & ) t = (t + y) % mod;

         y = (y + y) % mod;

         b >>= ;

     }

     return t;

 }

 ll modExp(ll a, ll b) {

     ll t = , y = a;

     while(b) {

         if(b & ) t = (fMul(t, y)) % mod;

         y = (fMul(y, y)) % mod;

         b >>= ;

     }

     return t;

 }

 int main()

 {

       scanf("%lld",&t);

       while(t--)

       {

           scanf("%lld%lld",&n,&k);

           ll sum=;

           for(int i=; i<n; i++)

           {

               scanf("%lld",&a[i]);

           }

           for(int i=; i<n; i++)

           {

               a[i]=((a[i]%mod)+mod)%mod;

               ll c=modExp(a[i],k);

               sum=(sum+c)%mod;

           }

           printf("%lld\n",sum);

       }

       return ;

 }