func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long n, m;     cin >> n >> m;     long long a = 1;     long long b = 1;     long long c = 1000000007;     for (int i = 0; i < n; i++) {       b = b * (2 * m - 1);       b = b + a;       b = b % c;       a = a * m;       a = a % c;     }     cout << b;     return 0;   }   