func_code_string: #include <bits/stdc++.h>   using namespace std;   long long mod = 1000000007;   long long N = mod;   long long quick_mod(long long a, long long b) {     long long ans = 1;     a %= N;     while (b) {       if (b % 2 != 0) {         ans = ans * a % N;         b--;       }       b /= 2;       a = a * a % N;     }     return ans % N;   }   int main() {     long long m, n, i, j, k;     while (cin >> m) {       if (m == 0) {         cout << 1 << endl;         continue;       }       cout << (quick_mod(2, m - 1) * (1 + quick_mod(2, m))) % N << endl;     }   }   